From 0ed23defed4e13a8485669279718de3f33f90ceb Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Wed, 15 Oct 2025 22:08:58 -0700
Subject: [PATCH 01/33] PPL tostring() implementation issue #4492

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 .../sql/calcite/utils/PPLOperandTypes.java    |   7 +
 .../function/PPLBuiltinOperators.java         |   2 +
 .../expression/function/PPLFuncImpTable.java  |   3 +
 .../function/udf/ToStringFunction.java        | 162 +++++++++++++++
 .../function/udf/ToStringFunctionTest.java    | 149 ++++++++++++++
 docs/user/ppl/functions/conversion.rst        |  92 +++++++++
 docs/user/ppl/functions/string.rst            |   3 +
 ppl/src/main/antlr/OpenSearchPPLLexer.g4      |   1 +
 ppl/src/main/antlr/OpenSearchPPLParser.g4     |   6 +-
 .../sql/ppl/parser/AstExpressionBuilder.java  |  11 +-
 .../calcite/CalcitePPLStringFunctionTest.java | 185 ++++++++++++++++++
 sql/src/main/antlr/OpenSearchSQLLexer.g4      |   1 +
 sql/src/main/antlr/OpenSearchSQLParser.g4     |   1 +
 13 files changed, 621 insertions(+), 2 deletions(-)
 create mode 100644 core/src/main/java/org/opensearch/sql/expression/function/udf/ToStringFunction.java
 create mode 100644 core/src/test/java/org/opensearch/sql/expression/function/udf/ToStringFunctionTest.java

diff --git a/core/src/main/java/org/opensearch/sql/calcite/utils/PPLOperandTypes.java b/core/src/main/java/org/opensearch/sql/calcite/utils/PPLOperandTypes.java
index 12a9a297542..69e1492538c 100644
--- a/core/src/main/java/org/opensearch/sql/calcite/utils/PPLOperandTypes.java
+++ b/core/src/main/java/org/opensearch/sql/calcite/utils/PPLOperandTypes.java
@@ -112,6 +112,13 @@ private PPLOperandTypes() {}
               SqlTypeFamily.INTEGER,
               SqlTypeFamily.INTEGER));
 
+  public static final UDFOperandMetadata BOOLEAN_OR_NUMERIC_STRING_OR_STRING_STRING =
+      UDFOperandMetadata.wrap(
+          (CompositeOperandTypeChecker)
+              OperandTypes.family(SqlTypeFamily.BOOLEAN)
+                  .or(OperandTypes.family(SqlTypeFamily.NUMERIC, SqlTypeFamily.STRING))
+                      .or(OperandTypes.family(SqlTypeFamily.STRING, SqlTypeFamily.STRING)));
+
   public static final UDFOperandMetadata NUMERIC_NUMERIC_OPTIONAL_NUMERIC =
       UDFOperandMetadata.wrap(
           (CompositeOperandTypeChecker)
diff --git a/core/src/main/java/org/opensearch/sql/expression/function/PPLBuiltinOperators.java b/core/src/main/java/org/opensearch/sql/expression/function/PPLBuiltinOperators.java
index 76f625ebd38..984f398b1ee 100644
--- a/core/src/main/java/org/opensearch/sql/expression/function/PPLBuiltinOperators.java
+++ b/core/src/main/java/org/opensearch/sql/expression/function/PPLBuiltinOperators.java
@@ -66,6 +66,7 @@
 import org.opensearch.sql.expression.function.udf.RexExtractMultiFunction;
 import org.opensearch.sql.expression.function.udf.RexOffsetFunction;
 import org.opensearch.sql.expression.function.udf.SpanFunction;
+import org.opensearch.sql.expression.function.udf.ToStringFunction;
 import org.opensearch.sql.expression.function.udf.condition.EarliestFunction;
 import org.opensearch.sql.expression.function.udf.condition.EnhancedCoalesceFunction;
 import org.opensearch.sql.expression.function.udf.condition.LatestFunction;
@@ -411,6 +412,7 @@ public class PPLBuiltinOperators extends ReflectiveSqlOperatorTable {
       RELEVANCE_QUERY_FUNCTION_INSTANCE.toUDF("multi_match", false);
   public static final SqlOperator NUMBER_TO_STRING =
       new NumberToStringFunction().toUDF("NUMBER_TO_STRING");
+  public static final SqlOperator TOSTRING = new ToStringFunction().toUDF("TOSTRING");
   public static final SqlOperator WIDTH_BUCKET =
       new org.opensearch.sql.expression.function.udf.binning.WidthBucketFunction()
           .toUDF("WIDTH_BUCKET");
diff --git a/core/src/main/java/org/opensearch/sql/expression/function/PPLFuncImpTable.java b/core/src/main/java/org/opensearch/sql/expression/function/PPLFuncImpTable.java
index 8297ecf73ce..de89df383d2 100644
--- a/core/src/main/java/org/opensearch/sql/expression/function/PPLFuncImpTable.java
+++ b/core/src/main/java/org/opensearch/sql/expression/function/PPLFuncImpTable.java
@@ -210,6 +210,7 @@
 import static org.opensearch.sql.expression.function.BuiltinFunctionName.TIMESTAMPDIFF;
 import static org.opensearch.sql.expression.function.BuiltinFunctionName.TIME_FORMAT;
 import static org.opensearch.sql.expression.function.BuiltinFunctionName.TIME_TO_SEC;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.TOSTRING;
 import static org.opensearch.sql.expression.function.BuiltinFunctionName.TO_DAYS;
 import static org.opensearch.sql.expression.function.BuiltinFunctionName.TO_SECONDS;
 import static org.opensearch.sql.expression.function.BuiltinFunctionName.TRANSFORM;
@@ -887,6 +888,7 @@ void populate() {
       registerOperator(WEEKOFYEAR, PPLBuiltinOperators.WEEK);
 
       registerOperator(INTERNAL_PATTERN_PARSER, PPLBuiltinOperators.PATTERN_PARSER);
+      registerOperator(TOSTRING, PPLBuiltinOperators.TOSTRING);
 
       // Register MVJOIN to use Calcite's ARRAY_JOIN
       register(
@@ -1058,6 +1060,7 @@ void populate() {
                               SqlTypeFamily.INTEGER,
                               SqlTypeFamily.INTEGER)),
               false));
+
       register(
           LOG,
           (FunctionImp2)
diff --git a/core/src/main/java/org/opensearch/sql/expression/function/udf/ToStringFunction.java b/core/src/main/java/org/opensearch/sql/expression/function/udf/ToStringFunction.java
new file mode 100644
index 00000000000..70d2a82b13c
--- /dev/null
+++ b/core/src/main/java/org/opensearch/sql/expression/function/udf/ToStringFunction.java
@@ -0,0 +1,162 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.sql.expression.function.udf;
+
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.text.NumberFormat;
+import java.time.Duration;
+import java.util.List;
+import java.util.Locale;
+import org.apache.calcite.adapter.enumerable.NotNullImplementor;
+import org.apache.calcite.adapter.enumerable.NullPolicy;
+import org.apache.calcite.adapter.enumerable.RexToLixTranslator;
+import org.apache.calcite.linq4j.function.Strict;
+import org.apache.calcite.linq4j.tree.Expression;
+import org.apache.calcite.linq4j.tree.Expressions;
+import org.apache.calcite.rex.RexCall;
+import org.apache.calcite.sql.type.SqlReturnTypeInference;
+import org.opensearch.sql.calcite.utils.PPLOperandTypes;
+import org.opensearch.sql.calcite.utils.PPLReturnTypes;
+import org.opensearch.sql.expression.function.ImplementorUDF;
+import org.opensearch.sql.expression.function.UDFOperandMetadata;
+
+/**
+ * A custom implementation of number/boolean to string .
+ *
+ * <p>This operator is necessary because tostring has following requirements "binary" Converts a
+ * number to a binary value. "hex" Converts the number to a hexadecimal value. "commas" Formats the
+ * number with commas. If the number includes a decimal, the function rounds the number to nearest
+ * two decimal places. "duration" Converts the value in seconds to the readable time format
+ * HH:MM:SS. if not format parameter provided, then consider value as boolean
+ */
+public class ToStringFunction extends ImplementorUDF {
+  public ToStringFunction() {
+    super(
+        new org.opensearch.sql.expression.function.udf.ToStringFunction.ToStringImplementor(),
+        NullPolicy.ANY);
+  }
+
+  public static final String DURATION_FORMAT = "duration";
+  public static final String HEX_FORMAT = "hex";
+  public static final String COMMAS_FORMAT = "commas";
+  public static final String BINARY_FORMAT = "binary";
+
+  @Override
+  public SqlReturnTypeInference getReturnTypeInference() {
+    return PPLReturnTypes.STRING_FORCE_NULLABLE;
+  }
+
+  @Override
+  public UDFOperandMetadata getOperandMetadata() {
+    return PPLOperandTypes.BOOLEAN_OR_NUMERIC_STRING_OR_STRING_STRING;
+  }
+
+  public static class ToStringImplementor implements NotNullImplementor {
+
+    @Override
+    public Expression implement(
+        RexToLixTranslator translator, RexCall call, List<Expression> translatedOperands) {
+      Expression fieldValue = translatedOperands.get(0);
+      if (translatedOperands.size() > 1) {
+        Expression format = translatedOperands.get(1);
+        return Expressions.call(ToStringFunction.class, "toString", fieldValue, format);
+      } else {
+        return Expressions.call(ToStringFunction.class, "toString", fieldValue);
+      }
+    }
+  }
+
+  @Strict
+  public static String toString(boolean fieldValue) {
+    if (fieldValue) {
+      return "True";
+    } else {
+      return "False";
+    }
+  }
+
+  @Strict
+  public static String toString(String fieldValue) {
+    return toString(Boolean.parseBoolean(fieldValue));
+  }
+
+  @Strict
+  public static String toString(BigDecimal num, String format) {
+    if (format.equals(DURATION_FORMAT)) {
+      Duration d = Duration.ofSeconds(num.toBigInteger().longValue());
+      long hours = d.toHours();
+      int minutes = d.toMinutesPart();
+      int remainingSeconds = d.toSecondsPart();
+
+      String time_str = String.format("%02d:%02d:%02d", hours, minutes, remainingSeconds);
+      return time_str;
+    } else if (format.equals(HEX_FORMAT)) {
+      return num.toBigInteger().toString(16);
+    } else if (format.equals(COMMAS_FORMAT)) {
+      NumberFormat nf = NumberFormat.getNumberInstance(Locale.getDefault());
+      nf.setMinimumFractionDigits(0);
+      nf.setMaximumFractionDigits(2);
+      return nf.format(num);
+
+    } else if (format.equals(BINARY_FORMAT)) {
+      BigInteger integerPart = num.toBigInteger(); // 42
+      return integerPart.toString(2);
+    }
+    return num.toString();
+  }
+
+  @Strict
+  public static String toString(double num, String format) {
+    if (format.equals(DURATION_FORMAT)) {
+      Duration d = Duration.ofSeconds(Math.round(num));
+      long hours = d.toHours();
+      int minutes = d.toMinutesPart();
+      int remainingSeconds = d.toSecondsPart();
+      String time_str = String.format("%02d:%02d:%02d", hours, minutes, remainingSeconds);
+      return time_str;
+    } else if (format.equals(HEX_FORMAT)) {
+      return Double.toHexString(num);
+    } else if (format.equals(COMMAS_FORMAT)) {
+      NumberFormat nf = NumberFormat.getNumberInstance(Locale.getDefault());
+      return nf.format(num);
+    } else if (format.equals(BINARY_FORMAT)) {
+      return Long.toBinaryString(Double.doubleToLongBits(num));
+    }
+    return Double.toString(num);
+  }
+
+  @Strict
+  public static String toString(int num, String format) {
+
+    if (format.equals(DURATION_FORMAT)) {
+
+      int hours = num / 3600;
+      int minutes = (num % 3600) / 60;
+      int seconds = num % 60;
+
+      String time_str = String.format("%02d:%02d:%02d", hours, minutes, seconds);
+      return time_str;
+    } else if (format.equals(HEX_FORMAT)) {
+      return Integer.toHexString(num);
+    } else if (format.equals(COMMAS_FORMAT)) {
+      NumberFormat nf = NumberFormat.getNumberInstance(Locale.getDefault());
+      return nf.format(num);
+    } else if (format.equals(BINARY_FORMAT)) {
+      return Integer.toBinaryString(num);
+    }
+    return Integer.toString(num);
+  }
+
+  @Strict
+  public static String toString(String str, String format) {
+    if (str.contains(".") || (str.length() > 10)) {
+      return toString(Double.parseDouble(str), format);
+    } else {
+      return toString(Integer.parseInt(str), format);
+    }
+  }
+}
diff --git a/core/src/test/java/org/opensearch/sql/expression/function/udf/ToStringFunctionTest.java b/core/src/test/java/org/opensearch/sql/expression/function/udf/ToStringFunctionTest.java
new file mode 100644
index 00000000000..cfd25796b23
--- /dev/null
+++ b/core/src/test/java/org/opensearch/sql/expression/function/udf/ToStringFunctionTest.java
@@ -0,0 +1,149 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.sql.expression.function.udf;
+
+import org.junit.jupiter.api.Test;
+
+import java.math.BigDecimal;
+import java.util.Locale;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class ToStringFunctionTest {
+
+  private final ToStringFunction function = new ToStringFunction();
+
+    @Test
+    void testBooleanToString() {
+        assertEquals("True", ToStringFunction.toString(true));
+        assertEquals("False", ToStringFunction.toString(false));
+    }
+
+    @Test
+    void testStringBooleanToString() {
+        assertEquals("True", ToStringFunction.toString("true"));
+        assertEquals("False", ToStringFunction.toString("false"));
+        assertEquals("False", ToStringFunction.toString("anythingElse"));
+    }
+
+    @Test
+    void testBigDecimalToStringDurationFormat() {
+        BigDecimal num = new BigDecimal("3661"); // 1 hour 1 minute 1 second
+        String result = ToStringFunction.toString(num, ToStringFunction.DURATION_FORMAT);
+        assertEquals("01:01:01", result);
+    }
+
+    @Test
+    void testBigDecimalToStringHexFormat() {
+        BigDecimal num = new BigDecimal("255");
+        String result = ToStringFunction.toString(num, ToStringFunction.HEX_FORMAT);
+        assertEquals("ff", result);
+    }
+
+    @Test
+    void testBigDecimalToStringCommasFormat() {
+        Locale.setDefault(Locale.US); // Ensure predictable comma placement
+        BigDecimal num = new BigDecimal("1234567.891");
+        String result = ToStringFunction.toString(num, ToStringFunction.COMMAS_FORMAT);
+        assertTrue(result.contains(","));
+    }
+
+    @Test
+    void testBigDecimalToStringBinaryFormat() {
+        BigDecimal num = new BigDecimal("10");
+        String result = ToStringFunction.toString(num, ToStringFunction.BINARY_FORMAT);
+        assertEquals("1010", result);
+    }
+
+    @Test
+    void testBigDecimalToStringDefault() {
+        BigDecimal num = new BigDecimal("123.45");
+        assertEquals("123.45", ToStringFunction.toString(num, "unknown"));
+    }
+
+    @Test
+    void testDoubleToStringDurationFormat() {
+        double num = 3661.4;
+        String result = ToStringFunction.toString(num, ToStringFunction.DURATION_FORMAT);
+        assertEquals("01:01:01", result);
+    }
+
+    @Test
+    void testDoubleToStringHexFormat() {
+        double num = 10.5;
+        String result = ToStringFunction.toString(num, ToStringFunction.HEX_FORMAT);
+        assertTrue(result.startsWith("0x"));
+    }
+
+    @Test
+    void testDoubleToStringCommasFormat() {
+        Locale.setDefault(Locale.US);
+        double num = 12345.678;
+        String result = ToStringFunction.toString(num, ToStringFunction.COMMAS_FORMAT);
+        assertTrue(result.contains(","));
+    }
+
+    @Test
+    void testDoubleToStringBinaryFormat() {
+        double num = 10.0;
+        String result = ToStringFunction.toString(num, ToStringFunction.BINARY_FORMAT);
+        assertNotNull(result);
+        assertFalse(result.isEmpty());
+    }
+
+    @Test
+    void testDoubleToStringDefault() {
+        assertEquals("10.5", ToStringFunction.toString(10.5, "unknown"));
+    }
+
+    @Test
+    void testIntToStringDurationFormat() {
+        int num = 3661;
+        String result = ToStringFunction.toString(num, ToStringFunction.DURATION_FORMAT);
+        assertEquals("01:01:01", result);
+    }
+
+    @Test
+    void testIntToStringHexFormat() {
+        assertEquals("ff", ToStringFunction.toString(255, ToStringFunction.HEX_FORMAT));
+    }
+
+    @Test
+    void testIntToStringCommasFormat() {
+        Locale.setDefault(Locale.US);
+        String result = ToStringFunction.toString(1234567, ToStringFunction.COMMAS_FORMAT);
+        assertTrue(result.contains(","));
+    }
+
+    @Test
+    void testIntToStringBinaryFormat() {
+        assertEquals("1010", ToStringFunction.toString(10, ToStringFunction.BINARY_FORMAT));
+    }
+
+    @Test
+    void testIntToStringDefault() {
+        assertEquals("123", ToStringFunction.toString(123, "unknown"));
+    }
+
+    @Test
+    void testStringNumericToStringIntFormat() {
+        String result = ToStringFunction.toString("42", ToStringFunction.HEX_FORMAT);
+        assertEquals("2a", result);
+    }
+
+    @Test
+    void testStringNumericToStringDoubleFormat() {
+        String result = ToStringFunction.toString("42.5", ToStringFunction.COMMAS_FORMAT);
+        assertTrue(result.contains("42"));
+    }
+
+    @Test
+    void testStringLargeNumberAsDouble() {
+        String largeNum = "1234567890123";
+        String result = ToStringFunction.toString(largeNum, ToStringFunction.BINARY_FORMAT);
+        assertNotNull(result);
+    }
+}
diff --git a/docs/user/ppl/functions/conversion.rst b/docs/user/ppl/functions/conversion.rst
index dbe4403540c..21124c27edc 100644
--- a/docs/user/ppl/functions/conversion.rst
+++ b/docs/user/ppl/functions/conversion.rst
@@ -78,3 +78,95 @@ Cast function can be chained::
     |-------|
     | True  |
     +-------+
+
+TOSTRING
+-----
+
+Description
+>>>>>>>>>>>
+There are two available usage based on paraemter types and number of parameters.
+Usage with format type: tostring(number|string, string) converts the number in first argument  to provided format type string in second argument.
+         Return type: string
+Usage for boolean parameter without format type: tostring(boolean) converts the string to 'True' or 'False'.
+         Return type: string
+
+You can use this function with the eval commands and as part of eval expressions.
+The first  argument can be a number, number as string or boolean.
+If first  argument is a a number or number as string , second argument need to be format name.
+If first argument is boolean, then second argument is not needed.
+
+format types:
+a) "binary" Converts a number to a binary value.
+b) "hex" Converts the number to a hexadecimal value.
+c) "commas" Formats the number with commas. If the number includes a decimal, the function rounds the number to nearest two decimal places.
+d) "duration" Converts the value in seconds to the readable time format HH:MM:SS.
+The format argument is optional and is only used when the value argument is a number. The tostring function supports the following formats.
+
+Binary conversion
+You can use this function to convert a number to a string of its binary representation. For example, the result of the following function is 1001, because the binary representation of 9 is 1001.:
+eval result = tostring(9, "binary")
+
+For information about bitwise functions that you can use with the tostring function, see Bitwise functions.
+
+Basic examples
+The following example returns "True 0xF 12,345.68".
+... | eval n=tostring(1==1) + " " + tostring(15, "hex") + " " + tostring(12345.6789, "commas")
+The following example returns foo=615 and foo2=00:10:15. The 615 seconds is converted into minutes and seconds.
+
+... | eval foo=615 | eval foo2 = tostring(foo, "duration")
+The following example formats the column totalSales to display values with a currency symbol and commas. You must use a period between the currency value and the tostring function.
+
+Example::
+
+    os> source=people | eval `boolean_str` = tostring(1=1)| fields `boolean_str`
+    fetched rows / total rows = 1/1
+    +---------------------+
+    | boolean_str         |
+    |---------------------+
+    | True                |
+    +---------------------+
+    os> source=EMP |  eval salary_binary = tostring(SAL, "binary") | fields ENAME, salary_binary, SAL"
+    fetched rows / total rows = 1/1
+    +---------------+------------------+------------+
+    | ENAME         |   salary_binary  |  SAL       |
+    |---------------+------------------+------------+
+    | SMITH         | 1001110001000000 | 80000.00   |
+    +---------------+------------------+------------+
+    os> source=EMP |  eval salary_hex = tostring(SAL, "hex") | fields ENAME, salary_hex, SAL"
+    fetched rows / total rows = 1/1
+    +---------------+------------------+------------+
+    | ENAME         |   salary_hex  |  SAL          |
+    |---------------+------------------+------------+
+    | SMITH         |   13880       | 80000.00      |
+    +---------------+---------------+---------------+
+
+     os> source=EMP |  eval salary_commas = tostring(SAL, "commas") | fields ENAME, salary_commas, SAL"
+     fetched rows / total rows = 1/1
+    +---------------+------------------+------------+
+    | ENAME         |   salary_commas  |  SAL       |
+    |---------------+------------------+------------+
+    | SMITH         |   80,000         | 80000.00   |
+    +---------------+------------------+------------+
+
+
+        duration
+
+      os> source=EMP |  eval duration = tostring(6500, "duration") | fields ENAME, duration"
+          fetched rows / total rows = 1/1
+    +---------------+-------------+
+    | ENAME         |   duration  |
+    |---------------+-------------+
+    | SMITH         |   01:48:20  |
+    +---------------+-------------+
+
+Usage for boolean parameter without format type::
+
+Example::
+
+    os> source=people | eval `boolean_str` = tostring(1=1)| fields `boolean_str`
+    fetched rows / total rows = 1/1
+    +---------------------+
+    | boolean_str         |
+    |---------------------+
+    | True                |
+    +---------------------+
\ No newline at end of file
diff --git a/docs/user/ppl/functions/string.rst b/docs/user/ppl/functions/string.rst
index 24efa1434f5..43efed3c470 100644
--- a/docs/user/ppl/functions/string.rst
+++ b/docs/user/ppl/functions/string.rst
@@ -397,3 +397,6 @@ Example::
     |---------------------+---------------------|
     | HELLOWORLD          | HELLOWORLD          |
     +---------------------+---------------------+
+
+
+
diff --git a/ppl/src/main/antlr/OpenSearchPPLLexer.g4 b/ppl/src/main/antlr/OpenSearchPPLLexer.g4
index ba1e4960bb2..e528bb553ab 100644
--- a/ppl/src/main/antlr/OpenSearchPPLLexer.g4
+++ b/ppl/src/main/antlr/OpenSearchPPLLexer.g4
@@ -392,6 +392,7 @@ STRFTIME:                           'STRFTIME';
 // TEXT FUNCTIONS
 SUBSTR:                             'SUBSTR';
 SUBSTRING:                          'SUBSTRING';
+TOSTRING:                           'TOSTRING';
 LTRIM:                              'LTRIM';
 RTRIM:                              'RTRIM';
 TRIM:                               'TRIM';
diff --git a/ppl/src/main/antlr/OpenSearchPPLParser.g4 b/ppl/src/main/antlr/OpenSearchPPLParser.g4
index e13447b68e9..852c55c863c 100644
--- a/ppl/src/main/antlr/OpenSearchPPLParser.g4
+++ b/ppl/src/main/antlr/OpenSearchPPLParser.g4
@@ -847,11 +847,14 @@ evalFunctionCall
    : evalFunctionName LT_PRTHS functionArgs RT_PRTHS
    ;
 
-// cast function
+
+// cast, tostring function
 dataTypeFunctionCall
    : CAST LT_PRTHS logicalExpression AS convertedDataType RT_PRTHS
+   | TOSTRING LT_PRTHS functionArgs RT_PRTHS
    ;
 
+
 convertedDataType
    : typeName = DATE
    | typeName = TIME
@@ -1434,6 +1437,7 @@ searchableKeyWord
    | USING
    | VALUE
    | CAST
+   | TOSTRING
    | GET_FORMAT
    | EXTRACT
    | INTERVAL
diff --git a/ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java b/ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java
index f037376f5c2..1460a3efc9a 100644
--- a/ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java
+++ b/ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java
@@ -414,7 +414,16 @@ private Function buildFunction(
   /** Cast function. */
   @Override
   public UnresolvedExpression visitDataTypeFunctionCall(DataTypeFunctionCallContext ctx) {
-    return new Cast(visit(ctx.logicalExpression()), visit(ctx.convertedDataType()));
+    ParseTree rootNode = ctx.getChild(0);
+    String functionName = rootNode.getText();
+    final String mappedName =
+        FUNCTION_NAME_MAPPING.getOrDefault(functionName.toLowerCase(Locale.ROOT), functionName);
+
+    if (mappedName.equals("cast")) {
+      return new Cast(visit(ctx.logicalExpression()), visit(ctx.convertedDataType()));
+    } else {
+      return buildFunction(mappedName, ctx.functionArgs().functionArg());
+    }
   }
 
   @Override
diff --git a/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLStringFunctionTest.java b/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLStringFunctionTest.java
index 1e97052dea0..d41b2c22453 100644
--- a/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLStringFunctionTest.java
+++ b/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLStringFunctionTest.java
@@ -46,6 +46,191 @@ public void testLower() {
     verifyPPLToSparkSQL(root, expectedSparkSql);
   }
 
+  @Test
+  public void testToStringBoolean() {
+    String ppl = "source=EMP | eval boolean_value = tostring(1==1) | fields boolean_value |head 1";
+    RelNode root = getRelNode(ppl);
+    String expectedLogical =
+        "LogicalSort(fetch=[1])\n"
+            + "  LogicalProject(boolean_value=[TOSTRING(true)])\n"
+            + "    LogicalTableScan(table=[[scott, EMP]])\n";
+    String expectedResult = "boolean_value=True\n";
+    verifyLogical(root, expectedLogical);
+    verifyResult(root, expectedResult);
+
+    String expectedSparkSql =
+        "SELECT `TOSTRING`(TRUE) `boolean_value`\n" + "FROM `scott`.`EMP`\n" + "LIMIT 1";
+    verifyPPLToSparkSQL(root, expectedSparkSql);
+  }
+
+  @Test
+  public void testToStringBin() {
+    String ppl =
+        "source=EMP |  eval salary_binary = tostring(SAL, \"binary\") | fields ENAME,"
+            + " salary_binary, SAL";
+    RelNode root = getRelNode(ppl);
+    String expectedLogical =
+        "LogicalProject(ENAME=[$1], salary_binary=[TOSTRING($5, 'binary':VARCHAR)], SAL=[$5])\n"
+            + "  LogicalTableScan(table=[[scott, EMP]])\n";
+    String expectedResult =
+        "ENAME=SMITH; salary_binary=1100100000; SAL=800.00\n"
+            + "ENAME=ALLEN; salary_binary=11001000000; SAL=1600.00\n"
+            + "ENAME=WARD; salary_binary=10011100010; SAL=1250.00\n"
+            + "ENAME=JONES; salary_binary=101110011111; SAL=2975.00\n"
+            + "ENAME=MARTIN; salary_binary=10011100010; SAL=1250.00\n"
+            + "ENAME=BLAKE; salary_binary=101100100010; SAL=2850.00\n"
+            + "ENAME=CLARK; salary_binary=100110010010; SAL=2450.00\n"
+            + "ENAME=SCOTT; salary_binary=101110111000; SAL=3000.00\n"
+            + "ENAME=KING; salary_binary=1001110001000; SAL=5000.00\n"
+            + "ENAME=TURNER; salary_binary=10111011100; SAL=1500.00\n"
+            + "ENAME=ADAMS; salary_binary=10001001100; SAL=1100.00\n"
+            + "ENAME=JAMES; salary_binary=1110110110; SAL=950.00\n"
+            + "ENAME=FORD; salary_binary=101110111000; SAL=3000.00\n"
+            + "ENAME=MILLER; salary_binary=10100010100; SAL=1300.00\n";
+    verifyLogical(root, expectedLogical);
+    verifyResult(root, expectedResult);
+
+    String expectedSparkSql =
+        "SELECT `ENAME`, `TOSTRING`(`SAL`, 'binary') `salary_binary`, `SAL`\nFROM `scott`.`EMP`";
+    verifyPPLToSparkSQL(root, expectedSparkSql);
+  }
+
+  @Test
+  public void testToStringHex() {
+    String ppl =
+        "source=EMP |  eval salary_hex = tostring(SAL, \"hex\") | fields ENAME, salary_hex, SAL";
+    RelNode root = getRelNode(ppl);
+    String expectedLogical =
+        "LogicalProject(ENAME=[$1], salary_hex=[TOSTRING($5, 'hex':VARCHAR)], SAL=[$5])\n"
+            + "  LogicalTableScan(table=[[scott, EMP]])\n";
+    String expectedResult =
+        "ENAME=SMITH; salary_hex=320; SAL=800.00\n"
+            + "ENAME=ALLEN; salary_hex=640; SAL=1600.00\n"
+            + "ENAME=WARD; salary_hex=4e2; SAL=1250.00\n"
+            + "ENAME=JONES; salary_hex=b9f; SAL=2975.00\n"
+            + "ENAME=MARTIN; salary_hex=4e2; SAL=1250.00\n"
+            + "ENAME=BLAKE; salary_hex=b22; SAL=2850.00\n"
+            + "ENAME=CLARK; salary_hex=992; SAL=2450.00\n"
+            + "ENAME=SCOTT; salary_hex=bb8; SAL=3000.00\n"
+            + "ENAME=KING; salary_hex=1388; SAL=5000.00\n"
+            + "ENAME=TURNER; salary_hex=5dc; SAL=1500.00\n"
+            + "ENAME=ADAMS; salary_hex=44c; SAL=1100.00\n"
+            + "ENAME=JAMES; salary_hex=3b6; SAL=950.00\n"
+            + "ENAME=FORD; salary_hex=bb8; SAL=3000.00\n"
+            + "ENAME=MILLER; salary_hex=514; SAL=1300.00\n";
+    verifyLogical(root, expectedLogical);
+    verifyResult(root, expectedResult);
+
+    String expectedSparkSql =
+        "SELECT `ENAME`, `TOSTRING`(`SAL`, 'hex') `salary_hex`, `SAL`\nFROM `scott`.`EMP`";
+    verifyPPLToSparkSQL(root, expectedSparkSql);
+  }
+
+    @Test
+    public void testToStringHexFromNumberAsString() {
+        String ppl =
+                "source=EMP |  eval salary_hex = tostring(\"1600\", \"hex\") | fields ENAME, salary_hex| head 1";
+        RelNode root = getRelNode(ppl);
+        String expectedLogical =
+                "LogicalSort(fetch=[1])\n  LogicalProject(ENAME=[$1], salary_hex=[TOSTRING('1600':VARCHAR, 'hex':VARCHAR)])\n    LogicalTableScan(table=[[scott, EMP]])\n";
+        String expectedResult =
+                "ENAME=SMITH; salary_hex=640\n";
+        verifyLogical(root, expectedLogical);
+        verifyResult(root, expectedResult);
+
+        String expectedSparkSql =
+                "SELECT `ENAME`, `TOSTRING`('1600', 'hex') `salary_hex`\nFROM `scott`.`EMP`\nLIMIT 1";
+        verifyPPLToSparkSQL(root, expectedSparkSql);
+    }
+
+    @Test
+    public void testToStringCommaFromNumberAsString() {
+        String ppl =
+                "source=EMP |  eval salary_comma = tostring(\"160040222\", \"commas\") | fields ENAME, salary_comma| head 1";
+        RelNode root = getRelNode(ppl);
+        String expectedLogical =
+                "LogicalSort(fetch=[1])\n  LogicalProject(ENAME=[$1], salary_comma=[TOSTRING('160040222':VARCHAR, 'commas':VARCHAR)])\n    LogicalTableScan(table=[[scott, EMP]])\n";
+        String expectedResult =
+                "ENAME=SMITH; salary_comma=160,040,222\n";
+        verifyLogical(root, expectedLogical);
+        verifyResult(root, expectedResult);
+
+        String expectedSparkSql =
+                "SELECT `ENAME`, `TOSTRING`('160040222', 'commas') `salary_comma`\nFROM `scott`.`EMP`\nLIMIT 1";
+        verifyPPLToSparkSQL(root, expectedSparkSql);
+    }
+    @Test
+    public void testToStringBinaryFromNumberAsString() {
+        String ppl =
+                "source=EMP |  eval salary_binary = tostring(\"160040222\", \"binary\") | fields ENAME, salary_binary| head 1";
+        RelNode root = getRelNode(ppl);
+        String expectedLogical =
+                "LogicalSort(fetch=[1])\n  LogicalProject(ENAME=[$1], salary_binary=[TOSTRING('160040222':VARCHAR, 'binary':VARCHAR)])\n    LogicalTableScan(table=[[scott, EMP]])\n";
+        String expectedResult =
+                "ENAME=SMITH; salary_binary=1001100010100000010100011110\n";
+        verifyLogical(root, expectedLogical);
+        verifyResult(root, expectedResult);
+
+        String expectedSparkSql =
+                "SELECT `ENAME`, `TOSTRING`('160040222', 'binary') `salary_binary`\nFROM `scott`.`EMP`\nLIMIT 1";
+        verifyPPLToSparkSQL(root, expectedSparkSql);
+    }
+    @Test
+  public void testToStringCommas() {
+    String ppl =
+        "source=EMP |  eval salary_commas = tostring(SAL, \"commas\") | fields ENAME,"
+            + " salary_commas, SAL";
+    RelNode root = getRelNode(ppl);
+
+    String expectedLogical =
+        "LogicalProject(ENAME=[$1], salary_commas=[TOSTRING($5, 'commas':VARCHAR)], SAL=[$5])\n"
+            + "  LogicalTableScan(table=[[scott, EMP]])\n";
+    String expectedResult =
+        "ENAME=SMITH; salary_commas=800; SAL=800.00\n"
+            + "ENAME=ALLEN; salary_commas=1,600; SAL=1600.00\n"
+            + "ENAME=WARD; salary_commas=1,250; SAL=1250.00\n"
+            + "ENAME=JONES; salary_commas=2,975; SAL=2975.00\n"
+            + "ENAME=MARTIN; salary_commas=1,250; SAL=1250.00\n"
+            + "ENAME=BLAKE; salary_commas=2,850; SAL=2850.00\n"
+            + "ENAME=CLARK; salary_commas=2,450; SAL=2450.00\n"
+            + "ENAME=SCOTT; salary_commas=3,000; SAL=3000.00\n"
+            + "ENAME=KING; salary_commas=5,000; SAL=5000.00\n"
+            + "ENAME=TURNER; salary_commas=1,500; SAL=1500.00\n"
+            + "ENAME=ADAMS; salary_commas=1,100; SAL=1100.00\n"
+            + "ENAME=JAMES; salary_commas=950; SAL=950.00\n"
+            + "ENAME=FORD; salary_commas=3,000; SAL=3000.00\n"
+            + "ENAME=MILLER; salary_commas=1,300; SAL=1300.00\n";
+    verifyLogical(root, expectedLogical);
+    verifyResult(root, expectedResult);
+
+    String expectedSparkSql =
+        "SELECT `ENAME`, `TOSTRING`(`SAL`, 'commas') `salary_commas`, `SAL`\nFROM `scott`.`EMP`";
+    verifyPPLToSparkSQL(root, expectedSparkSql);
+  }
+
+  @Test
+  public void testToStringDuration() {
+    String ppl =
+        "source=EMP |  eval duration_commas = tostring(6500, \"duration\") | fields ENAME,"
+            + " duration_commas|HEAD 1";
+
+    RelNode root = getRelNode(ppl);
+
+    String expectedLogical =
+        "LogicalSort(fetch=[1])\n"
+            + "  LogicalProject(ENAME=[$1], duration_commas=[TOSTRING(6500, 'duration':VARCHAR)])\n"
+            + "    LogicalTableScan(table=[[scott, EMP]])\n";
+    String expectedResult = "ENAME=SMITH; duration_commas=01:48:20\n";
+    verifyLogical(root, expectedLogical);
+    verifyResult(root, expectedResult);
+
+    String expectedSparkSql =
+        "SELECT `ENAME`, `TOSTRING`(6500, 'duration') `duration_commas`\n"
+            + "FROM `scott`.`EMP`\n"
+            + "LIMIT 1";
+    verifyPPLToSparkSQL(root, expectedSparkSql);
+  }
+
   @Test
   public void testLike() {
     String ppl = "source=EMP | where like(JOB, 'SALE%') | stats count() as cnt";
diff --git a/sql/src/main/antlr/OpenSearchSQLLexer.g4 b/sql/src/main/antlr/OpenSearchSQLLexer.g4
index ba7c5be85ab..6465c692da3 100644
--- a/sql/src/main/antlr/OpenSearchSQLLexer.g4
+++ b/sql/src/main/antlr/OpenSearchSQLLexer.g4
@@ -133,6 +133,7 @@ STDDEV_SAMP:                        'STDDEV_SAMP';
 
 SUBSTRING:                          'SUBSTRING';
 TRIM:                               'TRIM';
+TOSTRING:                           'TOSTRING';
 
 // Keywords, but can be ID
 // Common Keywords, but can be ID
diff --git a/sql/src/main/antlr/OpenSearchSQLParser.g4 b/sql/src/main/antlr/OpenSearchSQLParser.g4
index 5f7361160b3..fbaef12fb98 100644
--- a/sql/src/main/antlr/OpenSearchSQLParser.g4
+++ b/sql/src/main/antlr/OpenSearchSQLParser.g4
@@ -417,6 +417,7 @@ specificFunction
    : CASE expression caseFuncAlternative+ (ELSE elseArg = functionArg)? END     # caseFunctionCall
    | CASE caseFuncAlternative+ (ELSE elseArg = functionArg)? END                # caseFunctionCall
    | CAST '(' expression AS convertedDataType ')'                               # dataTypeFunctionCall
+   | TOSTRING '(' functionArg  ')'                                              # dataTypeFunctionCall
    ;
 
 relevanceFunction

From 5a5b778cdf83230ff8a68a259a628e3ee0b3f318 Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Thu, 16 Oct 2025 09:33:26 -0700
Subject: [PATCH 02/33] removed sql changes

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 sql/src/main/antlr/OpenSearchSQLLexer.g4  | 1 -
 sql/src/main/antlr/OpenSearchSQLParser.g4 | 1 -
 2 files changed, 2 deletions(-)

diff --git a/sql/src/main/antlr/OpenSearchSQLLexer.g4 b/sql/src/main/antlr/OpenSearchSQLLexer.g4
index 6465c692da3..ba7c5be85ab 100644
--- a/sql/src/main/antlr/OpenSearchSQLLexer.g4
+++ b/sql/src/main/antlr/OpenSearchSQLLexer.g4
@@ -133,7 +133,6 @@ STDDEV_SAMP:                        'STDDEV_SAMP';
 
 SUBSTRING:                          'SUBSTRING';
 TRIM:                               'TRIM';
-TOSTRING:                           'TOSTRING';
 
 // Keywords, but can be ID
 // Common Keywords, but can be ID
diff --git a/sql/src/main/antlr/OpenSearchSQLParser.g4 b/sql/src/main/antlr/OpenSearchSQLParser.g4
index fbaef12fb98..5f7361160b3 100644
--- a/sql/src/main/antlr/OpenSearchSQLParser.g4
+++ b/sql/src/main/antlr/OpenSearchSQLParser.g4
@@ -417,7 +417,6 @@ specificFunction
    : CASE expression caseFuncAlternative+ (ELSE elseArg = functionArg)? END     # caseFunctionCall
    | CASE caseFuncAlternative+ (ELSE elseArg = functionArg)? END                # caseFunctionCall
    | CAST '(' expression AS convertedDataType ')'                               # dataTypeFunctionCall
-   | TOSTRING '(' functionArg  ')'                                              # dataTypeFunctionCall
    ;
 
 relevanceFunction

From 9d71a95f8487a7c5fa0e4cea8d11b4a3893efcaf Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Thu, 16 Oct 2025 09:50:53 -0700
Subject: [PATCH 03/33] doc changes

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 docs/user/ppl/functions/conversion.rst | 4 ++--
 docs/user/ppl/functions/string.rst     | 4 +---
 2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/docs/user/ppl/functions/conversion.rst b/docs/user/ppl/functions/conversion.rst
index 21124c27edc..33af0075431 100644
--- a/docs/user/ppl/functions/conversion.rst
+++ b/docs/user/ppl/functions/conversion.rst
@@ -95,14 +95,14 @@ The first  argument can be a number, number as string or boolean.
 If first  argument is a a number or number as string , second argument need to be format name.
 If first argument is boolean, then second argument is not needed.
 
-format types:
+Format types:
 a) "binary" Converts a number to a binary value.
 b) "hex" Converts the number to a hexadecimal value.
 c) "commas" Formats the number with commas. If the number includes a decimal, the function rounds the number to nearest two decimal places.
 d) "duration" Converts the value in seconds to the readable time format HH:MM:SS.
 The format argument is optional and is only used when the value argument is a number. The tostring function supports the following formats.
 
-Binary conversion
+Binary conversion:
 You can use this function to convert a number to a string of its binary representation. For example, the result of the following function is 1001, because the binary representation of 9 is 1001.:
 eval result = tostring(9, "binary")
 
diff --git a/docs/user/ppl/functions/string.rst b/docs/user/ppl/functions/string.rst
index 43efed3c470..c1dd52a5d89 100644
--- a/docs/user/ppl/functions/string.rst
+++ b/docs/user/ppl/functions/string.rst
@@ -397,6 +397,4 @@ Example::
     |---------------------+---------------------|
     | HELLOWORLD          | HELLOWORLD          |
     +---------------------+---------------------+
-
-
-
+    

From be2c2e264a8cc337940f3f1ae2152a15672ce2cb Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Thu, 16 Oct 2025 09:52:09 -0700
Subject: [PATCH 04/33] docs changes

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 docs/user/ppl/functions/conversion.rst | 12 ++++++------
 docs/user/ppl/functions/string.rst     |  3 +--
 2 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/docs/user/ppl/functions/conversion.rst b/docs/user/ppl/functions/conversion.rst
index 33af0075431..9d0bf6eab1b 100644
--- a/docs/user/ppl/functions/conversion.rst
+++ b/docs/user/ppl/functions/conversion.rst
@@ -85,15 +85,15 @@ TOSTRING
 Description
 >>>>>>>>>>>
 There are two available usage based on paraemter types and number of parameters.
-Usage with format type: tostring(number|string, string) converts the number in first argument  to provided format type string in second argument.
-         Return type: string
+Usage with format type: tostring(ANY, [format]) converts the number in first argument  to provided format type string in second argument.
+   Return type: string
 Usage for boolean parameter without format type: tostring(boolean) converts the string to 'True' or 'False'.
-         Return type: string
+   Return type: string
 
 You can use this function with the eval commands and as part of eval expressions.
 The first  argument can be a number, number as string or boolean.
-If first  argument is a a number or number as string , second argument need to be format name.
-If first argument is boolean, then second argument is not needed.
+If first argument can be any valid type , second argument is optional and if provided , it needs to be format name.
+If first argument is boolean, then second argument is not used even if its provided.
 
 Format types:
 a) "binary" Converts a number to a binary value.
@@ -108,7 +108,7 @@ eval result = tostring(9, "binary")
 
 For information about bitwise functions that you can use with the tostring function, see Bitwise functions.
 
-Basic examples
+Basic examples:
 The following example returns "True 0xF 12,345.68".
 ... | eval n=tostring(1==1) + " " + tostring(15, "hex") + " " + tostring(12345.6789, "commas")
 The following example returns foo=615 and foo2=00:10:15. The 615 seconds is converted into minutes and seconds.
diff --git a/docs/user/ppl/functions/string.rst b/docs/user/ppl/functions/string.rst
index c1dd52a5d89..01b9b85b882 100644
--- a/docs/user/ppl/functions/string.rst
+++ b/docs/user/ppl/functions/string.rst
@@ -396,5 +396,4 @@ Example::
     | UPPER('helloworld') | UPPER('HELLOWORLD') |
     |---------------------+---------------------|
     | HELLOWORLD          | HELLOWORLD          |
-    +---------------------+---------------------+
-    
+    +---------------------+---------------------+
\ No newline at end of file

From fc763a431cbbdcad3fe35ab3f0e70f334d0b12a6 Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Thu, 16 Oct 2025 10:00:16 -0700
Subject: [PATCH 05/33] reverted string doc changes

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 docs/user/ppl/functions/string.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/docs/user/ppl/functions/string.rst b/docs/user/ppl/functions/string.rst
index 01b9b85b882..24efa1434f5 100644
--- a/docs/user/ppl/functions/string.rst
+++ b/docs/user/ppl/functions/string.rst
@@ -396,4 +396,4 @@ Example::
     | UPPER('helloworld') | UPPER('HELLOWORLD') |
     |---------------------+---------------------|
     | HELLOWORLD          | HELLOWORLD          |
-    +---------------------+---------------------+
\ No newline at end of file
+    +---------------------+---------------------+

From a04eb14529029cf51d020e75ba5e7e6f921fb07c Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Thu, 16 Oct 2025 10:06:46 -0700
Subject: [PATCH 06/33] removed extra word

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 docs/user/ppl/functions/conversion.rst | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/docs/user/ppl/functions/conversion.rst b/docs/user/ppl/functions/conversion.rst
index 9d0bf6eab1b..58171d7cc72 100644
--- a/docs/user/ppl/functions/conversion.rst
+++ b/docs/user/ppl/functions/conversion.rst
@@ -91,7 +91,7 @@ Usage for boolean parameter without format type: tostring(boolean) converts the
    Return type: string
 
 You can use this function with the eval commands and as part of eval expressions.
-The first  argument can be a number, number as string or boolean.
+The first argument can be a number, number as string or boolean.
 If first argument can be any valid type , second argument is optional and if provided , it needs to be format name.
 If first argument is boolean, then second argument is not used even if its provided.
 
@@ -148,9 +148,6 @@ Example::
     | SMITH         |   80,000         | 80000.00   |
     +---------------+------------------+------------+
 
-
-        duration
-
       os> source=EMP |  eval duration = tostring(6500, "duration") | fields ENAME, duration"
           fetched rows / total rows = 1/1
     +---------------+-------------+

From 590a8e63add13b75fa90047cd2eca1ab4d802936 Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Thu, 16 Oct 2025 10:24:25 -0700
Subject: [PATCH 07/33] added any type

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 docs/user/ppl/functions/conversion.rst | 38 +++++++++++---------------
 1 file changed, 16 insertions(+), 22 deletions(-)

diff --git a/docs/user/ppl/functions/conversion.rst b/docs/user/ppl/functions/conversion.rst
index 58171d7cc72..c4ebe0505de 100644
--- a/docs/user/ppl/functions/conversion.rst
+++ b/docs/user/ppl/functions/conversion.rst
@@ -85,27 +85,22 @@ TOSTRING
 Description
 >>>>>>>>>>>
 There are two available usage based on paraemter types and number of parameters.
-Usage with format type: tostring(ANY, [format]) converts the number in first argument  to provided format type string in second argument.
+Usage with format type: tostring(ANY, [format]) converts the number in first argument  to provided format type string in second argument. If non number type, then it converts to default string representation.
    Return type: string
 Usage for boolean parameter without format type: tostring(boolean) converts the string to 'True' or 'False'.
    Return type: string
-
 You can use this function with the eval commands and as part of eval expressions.
-The first argument can be a number, number as string or boolean.
-If first argument can be any valid type , second argument is optional and if provided , it needs to be format name.
+
+If first argument can be any valid type , second argument is optional and if provided , it needs to be format name to convert to where first argument contains only numbers.
 If first argument is boolean, then second argument is not used even if its provided.
 
-Format types:
+Format types::
 a) "binary" Converts a number to a binary value.
 b) "hex" Converts the number to a hexadecimal value.
 c) "commas" Formats the number with commas. If the number includes a decimal, the function rounds the number to nearest two decimal places.
 d) "duration" Converts the value in seconds to the readable time format HH:MM:SS.
 The format argument is optional and is only used when the value argument is a number. The tostring function supports the following formats.
 
-Binary conversion:
-You can use this function to convert a number to a string of its binary representation. For example, the result of the following function is 1001, because the binary representation of 9 is 1001.:
-eval result = tostring(9, "binary")
-
 For information about bitwise functions that you can use with the tostring function, see Bitwise functions.
 
 Basic examples:
@@ -114,17 +109,11 @@ The following example returns "True 0xF 12,345.68".
 The following example returns foo=615 and foo2=00:10:15. The 615 seconds is converted into minutes and seconds.
 
 ... | eval foo=615 | eval foo2 = tostring(foo, "duration")
-The following example formats the column totalSales to display values with a currency symbol and commas. You must use a period between the currency value and the tostring function.
 
-Example::
 
-    os> source=people | eval `boolean_str` = tostring(1=1)| fields `boolean_str`
-    fetched rows / total rows = 1/1
-    +---------------------+
-    | boolean_str         |
-    |---------------------+
-    | True                |
-    +---------------------+
+
+You can use this function to convert a number to a string of its binary representation.
+Example::
     os> source=EMP |  eval salary_binary = tostring(SAL, "binary") | fields ENAME, salary_binary, SAL"
     fetched rows / total rows = 1/1
     +---------------+------------------+------------+
@@ -132,6 +121,10 @@ Example::
     |---------------+------------------+------------+
     | SMITH         | 1001110001000000 | 80000.00   |
     +---------------+------------------+------------+
+
+
+You can use this function to convert a number to a string of its hex representation.
+Example::
     os> source=EMP |  eval salary_hex = tostring(SAL, "hex") | fields ENAME, salary_hex, SAL"
     fetched rows / total rows = 1/1
     +---------------+------------------+------------+
@@ -140,6 +133,8 @@ Example::
     | SMITH         |   13880       | 80000.00      |
     +---------------+---------------+---------------+
 
+The following example formats the column totalSales to display values  with commas.
+Example::
      os> source=EMP |  eval salary_commas = tostring(SAL, "commas") | fields ENAME, salary_commas, SAL"
      fetched rows / total rows = 1/1
     +---------------+------------------+------------+
@@ -147,7 +142,8 @@ Example::
     |---------------+------------------+------------+
     | SMITH         |   80,000         | 80000.00   |
     +---------------+------------------+------------+
-
+The following example converts number of seconds to HH:MM:SS format representing hours, minutes and seconds.
+Example::
       os> source=EMP |  eval duration = tostring(6500, "duration") | fields ENAME, duration"
           fetched rows / total rows = 1/1
     +---------------+-------------+
@@ -156,10 +152,8 @@ Example::
     | SMITH         |   01:48:20  |
     +---------------+-------------+
 
-Usage for boolean parameter without format type::
-
+Example for boolean parameter.
 Example::
-
     os> source=people | eval `boolean_str` = tostring(1=1)| fields `boolean_str`
     fetched rows / total rows = 1/1
     +---------------------+

From 6938e2c08dfef04119f1e37802d0a3a9554a0d21 Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Thu, 16 Oct 2025 11:00:43 -0700
Subject: [PATCH 08/33] doc formatting fixes

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 docs/user/ppl/functions/conversion.rst | 38 ++++++++++++++++----------
 1 file changed, 24 insertions(+), 14 deletions(-)

diff --git a/docs/user/ppl/functions/conversion.rst b/docs/user/ppl/functions/conversion.rst
index c4ebe0505de..280befee0aa 100644
--- a/docs/user/ppl/functions/conversion.rst
+++ b/docs/user/ppl/functions/conversion.rst
@@ -80,40 +80,44 @@ Cast function can be chained::
     +-------+
 
 TOSTRING
------
+-----------
 
 Description
 >>>>>>>>>>>
-There are two available usage based on paraemter types and number of parameters.
-Usage with format type: tostring(ANY, [format]) converts the number in first argument  to provided format type string in second argument. If non number type, then it converts to default string representation.
-   Return type: string
-Usage for boolean parameter without format type: tostring(boolean) converts the string to 'True' or 'False'.
-   Return type: string
-You can use this function with the eval commands and as part of eval expressions.
+The following usage options are available, depending on the parameter types and the number of parameters.
 
-If first argument can be any valid type , second argument is optional and if provided , it needs to be format name to convert to where first argument contains only numbers.
-If first argument is boolean, then second argument is not used even if its provided.
+Usage with format type: tostring(ANY, [format]): Converts the number in first argument  to provided format type string in second argument. If non number type, then it converts to default string representation.
+Return type: string
+
+Usage for boolean parameter without format type tostring(boolean): Converts the string to 'True' or 'False'.
+Return type: string
+
+You can use this function with the eval commands and as part of eval expressions. If first argument can be any valid type , second argument is optional and if provided , it needs to be format name to convert to where first argument contains only numbers. If first argument is boolean, then second argument is not used even if its provided.
+
+Format types:
 
-Format types::
 a) "binary" Converts a number to a binary value.
 b) "hex" Converts the number to a hexadecimal value.
 c) "commas" Formats the number with commas. If the number includes a decimal, the function rounds the number to nearest two decimal places.
 d) "duration" Converts the value in seconds to the readable time format HH:MM:SS.
-The format argument is optional and is only used when the value argument is a number. The tostring function supports the following formats.
 
-For information about bitwise functions that you can use with the tostring function, see Bitwise functions.
+The format argument is optional and is only used when the value argument is a number. The tostring function supports the following formats.
 
 Basic examples:
+
 The following example returns "True 0xF 12,345.68".
-... | eval n=tostring(1==1) + " " + tostring(15, "hex") + " " + tostring(12345.6789, "commas")
+
+    ... | eval n=tostring(1==1) + " " + tostring(15, "hex") + " " + tostring(12345.6789, "commas")
+
 The following example returns foo=615 and foo2=00:10:15. The 615 seconds is converted into minutes and seconds.
 
-... | eval foo=615 | eval foo2 = tostring(foo, "duration")
+    ... | eval foo=615 | eval foo2 = tostring(foo, "duration")
 
 
 
 You can use this function to convert a number to a string of its binary representation.
 Example::
+
     os> source=EMP |  eval salary_binary = tostring(SAL, "binary") | fields ENAME, salary_binary, SAL"
     fetched rows / total rows = 1/1
     +---------------+------------------+------------+
@@ -125,6 +129,7 @@ Example::
 
 You can use this function to convert a number to a string of its hex representation.
 Example::
+
     os> source=EMP |  eval salary_hex = tostring(SAL, "hex") | fields ENAME, salary_hex, SAL"
     fetched rows / total rows = 1/1
     +---------------+------------------+------------+
@@ -135,6 +140,7 @@ Example::
 
 The following example formats the column totalSales to display values  with commas.
 Example::
+
      os> source=EMP |  eval salary_commas = tostring(SAL, "commas") | fields ENAME, salary_commas, SAL"
      fetched rows / total rows = 1/1
     +---------------+------------------+------------+
@@ -142,8 +148,10 @@ Example::
     |---------------+------------------+------------+
     | SMITH         |   80,000         | 80000.00   |
     +---------------+------------------+------------+
+
 The following example converts number of seconds to HH:MM:SS format representing hours, minutes and seconds.
 Example::
+
       os> source=EMP |  eval duration = tostring(6500, "duration") | fields ENAME, duration"
           fetched rows / total rows = 1/1
     +---------------+-------------+
@@ -154,8 +162,10 @@ Example::
 
 Example for boolean parameter.
 Example::
+
     os> source=people | eval `boolean_str` = tostring(1=1)| fields `boolean_str`
     fetched rows / total rows = 1/1
+
     +---------------------+
     | boolean_str         |
     |---------------------+

From 314fccdaee8ab28ede0eab2f1da4e2b83cc24e96 Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Thu, 16 Oct 2025 11:04:06 -0700
Subject: [PATCH 09/33] description for boolean example

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 docs/user/ppl/functions/conversion.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/docs/user/ppl/functions/conversion.rst b/docs/user/ppl/functions/conversion.rst
index 280befee0aa..036a89daf00 100644
--- a/docs/user/ppl/functions/conversion.rst
+++ b/docs/user/ppl/functions/conversion.rst
@@ -160,7 +160,7 @@ Example::
     | SMITH         |   01:48:20  |
     +---------------+-------------+
 
-Example for boolean parameter.
+The following example for converts boolean parameter to string.
 Example::
 
     os> source=people | eval `boolean_str` = tostring(1=1)| fields `boolean_str`

From 0ee17b9a4a262a1d6070b98ae8a1162f6556f517 Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Fri, 17 Oct 2025 13:21:49 -0700
Subject: [PATCH 10/33] added format_time call from calcite , added
 duration_millis as splunk default duration is in seconds which will be used
 for duration format , added cast call for tostring with 1 argument

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 .../sql/calcite/utils/PPLOperandTypes.java    |   2 +-
 .../function/udf/ToStringFunction.java        |  53 ++--
 .../function/udf/ToStringFunctionTest.java    | 265 +++++++++---------
 .../sql/ppl/parser/AstExpressionBuilder.java  |  52 +++-
 .../calcite/CalcitePPLStringFunctionTest.java | 157 +++++++----
 5 files changed, 312 insertions(+), 217 deletions(-)

diff --git a/core/src/main/java/org/opensearch/sql/calcite/utils/PPLOperandTypes.java b/core/src/main/java/org/opensearch/sql/calcite/utils/PPLOperandTypes.java
index 69e1492538c..20811f1af48 100644
--- a/core/src/main/java/org/opensearch/sql/calcite/utils/PPLOperandTypes.java
+++ b/core/src/main/java/org/opensearch/sql/calcite/utils/PPLOperandTypes.java
@@ -117,7 +117,7 @@ private PPLOperandTypes() {}
           (CompositeOperandTypeChecker)
               OperandTypes.family(SqlTypeFamily.BOOLEAN)
                   .or(OperandTypes.family(SqlTypeFamily.NUMERIC, SqlTypeFamily.STRING))
-                      .or(OperandTypes.family(SqlTypeFamily.STRING, SqlTypeFamily.STRING)));
+                  .or(OperandTypes.family(SqlTypeFamily.STRING, SqlTypeFamily.STRING)));
 
   public static final UDFOperandMetadata NUMERIC_NUMERIC_OPTIONAL_NUMERIC =
       UDFOperandMetadata.wrap(
diff --git a/core/src/main/java/org/opensearch/sql/expression/function/udf/ToStringFunction.java b/core/src/main/java/org/opensearch/sql/expression/function/udf/ToStringFunction.java
index 70d2a82b13c..be76100f38d 100644
--- a/core/src/main/java/org/opensearch/sql/expression/function/udf/ToStringFunction.java
+++ b/core/src/main/java/org/opensearch/sql/expression/function/udf/ToStringFunction.java
@@ -8,7 +8,6 @@
 import java.math.BigDecimal;
 import java.math.BigInteger;
 import java.text.NumberFormat;
-import java.time.Duration;
 import java.util.List;
 import java.util.Locale;
 import org.apache.calcite.adapter.enumerable.NotNullImplementor;
@@ -18,6 +17,7 @@
 import org.apache.calcite.linq4j.tree.Expression;
 import org.apache.calcite.linq4j.tree.Expressions;
 import org.apache.calcite.rex.RexCall;
+import org.apache.calcite.runtime.SqlFunctions;
 import org.apache.calcite.sql.type.SqlReturnTypeInference;
 import org.opensearch.sql.calcite.utils.PPLOperandTypes;
 import org.opensearch.sql.calcite.utils.PPLReturnTypes;
@@ -41,9 +41,13 @@ public ToStringFunction() {
   }
 
   public static final String DURATION_FORMAT = "duration";
+  public static final String DURATION_MILLIS_FORMAT = "duration_millis";
   public static final String HEX_FORMAT = "hex";
   public static final String COMMAS_FORMAT = "commas";
   public static final String BINARY_FORMAT = "binary";
+  public static final SqlFunctions.DateFormatFunction dateTimeFormatter =
+      new SqlFunctions.DateFormatFunction();
+  public static final String format24hour = "%H:%M:%S"; // 24-hour format
 
   @Override
   public SqlReturnTypeInference getReturnTypeInference() {
@@ -65,7 +69,13 @@ public Expression implement(
         Expression format = translatedOperands.get(1);
         return Expressions.call(ToStringFunction.class, "toString", fieldValue, format);
       } else {
-        return Expressions.call(ToStringFunction.class, "toString", fieldValue);
+        // autoboxes to Boolean
+
+        if (!fieldValue.getType().getTypeName().equals("Boolean")) {
+          return Expressions.call(ToStringFunction.class, "toString", fieldValue);
+        } else {
+          return Expressions.call(ToStringFunction.class, "toString", fieldValue);
+        }
       }
     }
   }
@@ -87,13 +97,13 @@ public static String toString(String fieldValue) {
   @Strict
   public static String toString(BigDecimal num, String format) {
     if (format.equals(DURATION_FORMAT)) {
-      Duration d = Duration.ofSeconds(num.toBigInteger().longValue());
-      long hours = d.toHours();
-      int minutes = d.toMinutesPart();
-      int remainingSeconds = d.toSecondsPart();
 
-      String time_str = String.format("%02d:%02d:%02d", hours, minutes, remainingSeconds);
-      return time_str;
+      return dateTimeFormatter.formatTime(format24hour, num.toBigInteger().intValue() * 1000);
+
+    } else if (format.equals(DURATION_MILLIS_FORMAT)) {
+
+      return dateTimeFormatter.formatTime(format24hour, num.toBigInteger().intValue());
+
     } else if (format.equals(HEX_FORMAT)) {
       return num.toBigInteger().toString(16);
     } else if (format.equals(COMMAS_FORMAT)) {
@@ -112,12 +122,11 @@ public static String toString(BigDecimal num, String format) {
   @Strict
   public static String toString(double num, String format) {
     if (format.equals(DURATION_FORMAT)) {
-      Duration d = Duration.ofSeconds(Math.round(num));
-      long hours = d.toHours();
-      int minutes = d.toMinutesPart();
-      int remainingSeconds = d.toSecondsPart();
-      String time_str = String.format("%02d:%02d:%02d", hours, minutes, remainingSeconds);
-      return time_str;
+      return dateTimeFormatter.formatTime(format24hour, ((int) Math.round(num)) * 1000);
+    } else if (format.equals(DURATION_MILLIS_FORMAT)) {
+
+      return dateTimeFormatter.formatTime(format24hour, ((int) Math.round(num)));
+
     } else if (format.equals(HEX_FORMAT)) {
       return Double.toHexString(num);
     } else if (format.equals(COMMAS_FORMAT)) {
@@ -129,17 +138,19 @@ public static String toString(double num, String format) {
     return Double.toString(num);
   }
 
+  @Strict
+  public static String toString(short num, String format) {
+    int i = (int) num;
+    return toString(i, format);
+  }
+
   @Strict
   public static String toString(int num, String format) {
 
     if (format.equals(DURATION_FORMAT)) {
-
-      int hours = num / 3600;
-      int minutes = (num % 3600) / 60;
-      int seconds = num % 60;
-
-      String time_str = String.format("%02d:%02d:%02d", hours, minutes, seconds);
-      return time_str;
+      return dateTimeFormatter.formatTime(format24hour, num * 1000);
+    } else if (format.equals(DURATION_MILLIS_FORMAT)) {
+      return dateTimeFormatter.formatTime(format24hour, num);
     } else if (format.equals(HEX_FORMAT)) {
       return Integer.toHexString(num);
     } else if (format.equals(COMMAS_FORMAT)) {
diff --git a/core/src/test/java/org/opensearch/sql/expression/function/udf/ToStringFunctionTest.java b/core/src/test/java/org/opensearch/sql/expression/function/udf/ToStringFunctionTest.java
index cfd25796b23..f0867f93327 100644
--- a/core/src/test/java/org/opensearch/sql/expression/function/udf/ToStringFunctionTest.java
+++ b/core/src/test/java/org/opensearch/sql/expression/function/udf/ToStringFunctionTest.java
@@ -5,145 +5,144 @@
 
 package org.opensearch.sql.expression.function.udf;
 
-import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
 
 import java.math.BigDecimal;
 import java.util.Locale;
-
-import static org.junit.jupiter.api.Assertions.*;
+import org.junit.jupiter.api.Test;
 
 public class ToStringFunctionTest {
 
   private final ToStringFunction function = new ToStringFunction();
 
-    @Test
-    void testBooleanToString() {
-        assertEquals("True", ToStringFunction.toString(true));
-        assertEquals("False", ToStringFunction.toString(false));
-    }
-
-    @Test
-    void testStringBooleanToString() {
-        assertEquals("True", ToStringFunction.toString("true"));
-        assertEquals("False", ToStringFunction.toString("false"));
-        assertEquals("False", ToStringFunction.toString("anythingElse"));
-    }
-
-    @Test
-    void testBigDecimalToStringDurationFormat() {
-        BigDecimal num = new BigDecimal("3661"); // 1 hour 1 minute 1 second
-        String result = ToStringFunction.toString(num, ToStringFunction.DURATION_FORMAT);
-        assertEquals("01:01:01", result);
-    }
-
-    @Test
-    void testBigDecimalToStringHexFormat() {
-        BigDecimal num = new BigDecimal("255");
-        String result = ToStringFunction.toString(num, ToStringFunction.HEX_FORMAT);
-        assertEquals("ff", result);
-    }
-
-    @Test
-    void testBigDecimalToStringCommasFormat() {
-        Locale.setDefault(Locale.US); // Ensure predictable comma placement
-        BigDecimal num = new BigDecimal("1234567.891");
-        String result = ToStringFunction.toString(num, ToStringFunction.COMMAS_FORMAT);
-        assertTrue(result.contains(","));
-    }
-
-    @Test
-    void testBigDecimalToStringBinaryFormat() {
-        BigDecimal num = new BigDecimal("10");
-        String result = ToStringFunction.toString(num, ToStringFunction.BINARY_FORMAT);
-        assertEquals("1010", result);
-    }
-
-    @Test
-    void testBigDecimalToStringDefault() {
-        BigDecimal num = new BigDecimal("123.45");
-        assertEquals("123.45", ToStringFunction.toString(num, "unknown"));
-    }
-
-    @Test
-    void testDoubleToStringDurationFormat() {
-        double num = 3661.4;
-        String result = ToStringFunction.toString(num, ToStringFunction.DURATION_FORMAT);
-        assertEquals("01:01:01", result);
-    }
-
-    @Test
-    void testDoubleToStringHexFormat() {
-        double num = 10.5;
-        String result = ToStringFunction.toString(num, ToStringFunction.HEX_FORMAT);
-        assertTrue(result.startsWith("0x"));
-    }
-
-    @Test
-    void testDoubleToStringCommasFormat() {
-        Locale.setDefault(Locale.US);
-        double num = 12345.678;
-        String result = ToStringFunction.toString(num, ToStringFunction.COMMAS_FORMAT);
-        assertTrue(result.contains(","));
-    }
-
-    @Test
-    void testDoubleToStringBinaryFormat() {
-        double num = 10.0;
-        String result = ToStringFunction.toString(num, ToStringFunction.BINARY_FORMAT);
-        assertNotNull(result);
-        assertFalse(result.isEmpty());
-    }
-
-    @Test
-    void testDoubleToStringDefault() {
-        assertEquals("10.5", ToStringFunction.toString(10.5, "unknown"));
-    }
-
-    @Test
-    void testIntToStringDurationFormat() {
-        int num = 3661;
-        String result = ToStringFunction.toString(num, ToStringFunction.DURATION_FORMAT);
-        assertEquals("01:01:01", result);
-    }
-
-    @Test
-    void testIntToStringHexFormat() {
-        assertEquals("ff", ToStringFunction.toString(255, ToStringFunction.HEX_FORMAT));
-    }
-
-    @Test
-    void testIntToStringCommasFormat() {
-        Locale.setDefault(Locale.US);
-        String result = ToStringFunction.toString(1234567, ToStringFunction.COMMAS_FORMAT);
-        assertTrue(result.contains(","));
-    }
-
-    @Test
-    void testIntToStringBinaryFormat() {
-        assertEquals("1010", ToStringFunction.toString(10, ToStringFunction.BINARY_FORMAT));
-    }
-
-    @Test
-    void testIntToStringDefault() {
-        assertEquals("123", ToStringFunction.toString(123, "unknown"));
-    }
-
-    @Test
-    void testStringNumericToStringIntFormat() {
-        String result = ToStringFunction.toString("42", ToStringFunction.HEX_FORMAT);
-        assertEquals("2a", result);
-    }
-
-    @Test
-    void testStringNumericToStringDoubleFormat() {
-        String result = ToStringFunction.toString("42.5", ToStringFunction.COMMAS_FORMAT);
-        assertTrue(result.contains("42"));
-    }
-
-    @Test
-    void testStringLargeNumberAsDouble() {
-        String largeNum = "1234567890123";
-        String result = ToStringFunction.toString(largeNum, ToStringFunction.BINARY_FORMAT);
-        assertNotNull(result);
-    }
+  @Test
+  void testBooleanToString() {
+    assertEquals("True", ToStringFunction.toString(true));
+    assertEquals("False", ToStringFunction.toString(false));
+  }
+
+  @Test
+  void testStringBooleanToString() {
+    assertEquals("True", ToStringFunction.toString("true"));
+    assertEquals("False", ToStringFunction.toString("false"));
+    assertEquals("False", ToStringFunction.toString("anythingElse"));
+  }
+
+  @Test
+  void testBigDecimalToStringDurationFormat() {
+    BigDecimal num = new BigDecimal("3661"); // 1 hour 1 minute 1 second
+    String result = ToStringFunction.toString(num, ToStringFunction.DURATION_FORMAT);
+    assertEquals("01:01:01", result);
+  }
+
+  @Test
+  void testBigDecimalToStringHexFormat() {
+    BigDecimal num = new BigDecimal("255");
+    String result = ToStringFunction.toString(num, ToStringFunction.HEX_FORMAT);
+    assertEquals("ff", result);
+  }
+
+  @Test
+  void testBigDecimalToStringCommasFormat() {
+    Locale.setDefault(Locale.US); // Ensure predictable comma placement
+    BigDecimal num = new BigDecimal("1234567.891");
+    String result = ToStringFunction.toString(num, ToStringFunction.COMMAS_FORMAT);
+    assertTrue(result.contains(","));
+  }
+
+  @Test
+  void testBigDecimalToStringBinaryFormat() {
+    BigDecimal num = new BigDecimal("10");
+    String result = ToStringFunction.toString(num, ToStringFunction.BINARY_FORMAT);
+    assertEquals("1010", result);
+  }
+
+  @Test
+  void testBigDecimalToStringDefault() {
+    BigDecimal num = new BigDecimal("123.45");
+    assertEquals("123.45", ToStringFunction.toString(num, "unknown"));
+  }
+
+  @Test
+  void testDoubleToStringDurationFormat() {
+    double num = 3661.4;
+    String result = ToStringFunction.toString(num, ToStringFunction.DURATION_FORMAT);
+    assertEquals("01:01:01", result);
+  }
+
+  @Test
+  void testDoubleToStringHexFormat() {
+    double num = 10.5;
+    String result = ToStringFunction.toString(num, ToStringFunction.HEX_FORMAT);
+    assertTrue(result.startsWith("0x"));
+  }
+
+  @Test
+  void testDoubleToStringCommasFormat() {
+    Locale.setDefault(Locale.US);
+    double num = 12345.678;
+    String result = ToStringFunction.toString(num, ToStringFunction.COMMAS_FORMAT);
+    assertTrue(result.contains(","));
+  }
+
+  @Test
+  void testDoubleToStringBinaryFormat() {
+    double num = 10.0;
+    String result = ToStringFunction.toString(num, ToStringFunction.BINARY_FORMAT);
+    assertNotNull(result);
+    assertFalse(result.isEmpty());
+  }
+
+  @Test
+  void testDoubleToStringDefault() {
+    assertEquals("10.5", ToStringFunction.toString(10.5, "unknown"));
+  }
+
+  @Test
+  void testIntToStringDurationFormat() {
+    int num = 3661;
+    String result = ToStringFunction.toString(num, ToStringFunction.DURATION_FORMAT);
+    assertEquals("01:01:01", result);
+  }
+
+  @Test
+  void testIntToStringHexFormat() {
+    assertEquals("ff", ToStringFunction.toString(255, ToStringFunction.HEX_FORMAT));
+  }
+
+  @Test
+  void testIntToStringCommasFormat() {
+    Locale.setDefault(Locale.US);
+    String result = ToStringFunction.toString(1234567, ToStringFunction.COMMAS_FORMAT);
+    assertTrue(result.contains(","));
+  }
+
+  @Test
+  void testIntToStringBinaryFormat() {
+    assertEquals("1010", ToStringFunction.toString(10, ToStringFunction.BINARY_FORMAT));
+  }
+
+  @Test
+  void testIntToStringDefault() {
+    assertEquals("123", ToStringFunction.toString(123, "unknown"));
+  }
+
+  @Test
+  void testStringNumericToStringIntFormat() {
+    String result = ToStringFunction.toString("42", ToStringFunction.HEX_FORMAT);
+    assertEquals("2a", result);
+  }
+
+  @Test
+  void testStringNumericToStringDoubleFormat() {
+    String result = ToStringFunction.toString("42.5", ToStringFunction.COMMAS_FORMAT);
+    assertTrue(result.contains("42"));
+  }
+
+  @Test
+  void testStringLargeNumberAsDouble() {
+    String largeNum = "1234567890123";
+    String result = ToStringFunction.toString(largeNum, ToStringFunction.BINARY_FORMAT);
+    assertNotNull(result);
+  }
 }
diff --git a/ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java b/ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java
index 1460a3efc9a..2112282f728 100644
--- a/ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java
+++ b/ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java
@@ -19,6 +19,7 @@
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
 import java.util.stream.Stream;
+import org.antlr.v4.runtime.CommonTokenStream;
 import org.antlr.v4.runtime.ParserRuleContext;
 import org.antlr.v4.runtime.RuleContext;
 import org.antlr.v4.runtime.tree.ParseTree;
@@ -29,8 +30,10 @@
 import org.opensearch.sql.ast.expression.subquery.ScalarSubquery;
 import org.opensearch.sql.ast.tree.Trendline;
 import org.opensearch.sql.calcite.plan.OpenSearchConstants;
+import org.opensearch.sql.common.antlr.CaseInsensitiveCharStream;
 import org.opensearch.sql.common.antlr.SyntaxCheckException;
 import org.opensearch.sql.common.utils.StringUtils;
+import org.opensearch.sql.ppl.antlr.parser.OpenSearchPPLLexer;
 import org.opensearch.sql.ppl.antlr.parser.OpenSearchPPLParser;
 import org.opensearch.sql.ppl.antlr.parser.OpenSearchPPLParser.BinaryArithmeticContext;
 import org.opensearch.sql.ppl.antlr.parser.OpenSearchPPLParser.BooleanLiteralContext;
@@ -411,18 +414,51 @@ private Function buildFunction(
         functionName, args.stream().map(this::visitFunctionArg).collect(Collectors.toList()));
   }
 
+  public DataTypeFunctionCallContext createDataTypeFunctionCallContext(String castExpression) {
+    // Create a case-insensitive character stream from the input
+    CaseInsensitiveCharStream charStream = new CaseInsensitiveCharStream(castExpression);
+
+    // Create lexer and parser
+    OpenSearchPPLLexer lexer = new OpenSearchPPLLexer(charStream);
+    CommonTokenStream tokens = new CommonTokenStream(lexer);
+    OpenSearchPPLParser parser = new OpenSearchPPLParser(tokens);
+
+    // Parse the expression - cast is part of evalFunctionCall
+    DataTypeFunctionCallContext evalContext = parser.dataTypeFunctionCall();
+    return evalContext;
+  }
+
   /** Cast function. */
   @Override
   public UnresolvedExpression visitDataTypeFunctionCall(DataTypeFunctionCallContext ctx) {
-    ParseTree rootNode = ctx.getChild(0);
-    String functionName = rootNode.getText();
-    final String mappedName =
-        FUNCTION_NAME_MAPPING.getOrDefault(functionName.toLowerCase(Locale.ROOT), functionName);
-
-    if (mappedName.equals("cast")) {
-      return new Cast(visit(ctx.logicalExpression()), visit(ctx.convertedDataType()));
+    if (ctx.functionArgs() != null) {
+
+      ParseTree rootNode = ctx.getChild(0);
+      String functionName = rootNode.getText();
+      final String mappedName =
+          FUNCTION_NAME_MAPPING.getOrDefault(functionName.toLowerCase(Locale.ROOT), functionName);
+      System.out.println(mappedName);
+      if (mappedName != null && mappedName.equals("tostring")) {
+        if (ctx.functionArgs().functionArg().size() == 1) {
+          List<OpenSearchPPLParser.FunctionArgContext> functionArgs =
+              ctx.functionArgs().functionArg();
+
+          String castExpresstion =
+              String.format("cast( %s as String)", functionArgs.getFirst().getText());
+          DataTypeFunctionCallContext toStringDataTypeConversionContext =
+              this.createDataTypeFunctionCallContext(castExpresstion);
+          return new Cast(
+              visit(toStringDataTypeConversionContext.logicalExpression()),
+              visit(toStringDataTypeConversionContext.convertedDataType()));
+          //
+        } else {
+          return buildFunction(mappedName, ctx.functionArgs().functionArg());
+        }
+      } else {
+        return new Cast(visit(ctx.logicalExpression()), visit(ctx.convertedDataType()));
+      }
     } else {
-      return buildFunction(mappedName, ctx.functionArgs().functionArg());
+      return new Cast(visit(ctx.logicalExpression()), visit(ctx.convertedDataType()));
     }
   }
 
diff --git a/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLStringFunctionTest.java b/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLStringFunctionTest.java
index d41b2c22453..b32ecd04e3f 100644
--- a/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLStringFunctionTest.java
+++ b/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLStringFunctionTest.java
@@ -46,20 +46,55 @@ public void testLower() {
     verifyPPLToSparkSQL(root, expectedSparkSql);
   }
 
+  // This test evalutes tostring where it gets converted to cast call
+
+  @Test
+  public void testToStringFormatNotSpecified() {
+    String ppl =
+        "source=EMP | eval string_value = tostring(MGR) | eval cast_value = cast(MGR as string)|"
+            + " fields string_value, cast_value";
+    RelNode root = getRelNode(ppl);
+    String expectedLogical =
+        "LogicalProject(string_value=[SAFE_CAST($3)], cast_value=[SAFE_CAST($3)])\n"
+            + "  LogicalTableScan(table=[[scott, EMP]])\n";
+    String expectedResult =
+        "string_value=7902; cast_value=7902\n"
+            + "string_value=7698; cast_value=7698\n"
+            + "string_value=7698; cast_value=7698\n"
+            + "string_value=7839; cast_value=7839\n"
+            + "string_value=7698; cast_value=7698\n"
+            + "string_value=7839; cast_value=7839\n"
+            + "string_value=7839; cast_value=7839\n"
+            + "string_value=7566; cast_value=7566\n"
+            + "string_value=null; cast_value=null\n"
+            + "string_value=7698; cast_value=7698\n"
+            + "string_value=7788; cast_value=7788\n"
+            + "string_value=7698; cast_value=7698\n"
+            + "string_value=7566; cast_value=7566\n"
+            + "string_value=7782; cast_value=7782\n";
+    verifyLogical(root, expectedLogical);
+    verifyResult(root, expectedResult);
+
+    String expectedSparkSql =
+        "SELECT SAFE_CAST(`MGR` AS STRING) `string_value`, SAFE_CAST(`MGR` AS STRING)"
+            + " `cast_value`\n"
+            + "FROM `scott`.`EMP`";
+    verifyPPLToSparkSQL(root, expectedSparkSql);
+  }
+
   @Test
   public void testToStringBoolean() {
     String ppl = "source=EMP | eval boolean_value = tostring(1==1) | fields boolean_value |head 1";
     RelNode root = getRelNode(ppl);
     String expectedLogical =
         "LogicalSort(fetch=[1])\n"
-            + "  LogicalProject(boolean_value=[TOSTRING(true)])\n"
+            + "  LogicalProject(boolean_value=['TRUE':VARCHAR])\n"
             + "    LogicalTableScan(table=[[scott, EMP]])\n";
-    String expectedResult = "boolean_value=True\n";
+    String expectedResult = "boolean_value=TRUE\n";
     verifyLogical(root, expectedLogical);
     verifyResult(root, expectedResult);
 
-    String expectedSparkSql =
-        "SELECT `TOSTRING`(TRUE) `boolean_value`\n" + "FROM `scott`.`EMP`\n" + "LIMIT 1";
+    String expectedSparkSql = "SELECT 'TRUE' `boolean_value`\nFROM `scott`.`EMP`\nLIMIT 1";
     verifyPPLToSparkSQL(root, expectedSparkSql);
   }
 
@@ -126,56 +161,70 @@ public void testToStringHex() {
     verifyPPLToSparkSQL(root, expectedSparkSql);
   }
 
-    @Test
-    public void testToStringHexFromNumberAsString() {
-        String ppl =
-                "source=EMP |  eval salary_hex = tostring(\"1600\", \"hex\") | fields ENAME, salary_hex| head 1";
-        RelNode root = getRelNode(ppl);
-        String expectedLogical =
-                "LogicalSort(fetch=[1])\n  LogicalProject(ENAME=[$1], salary_hex=[TOSTRING('1600':VARCHAR, 'hex':VARCHAR)])\n    LogicalTableScan(table=[[scott, EMP]])\n";
-        String expectedResult =
-                "ENAME=SMITH; salary_hex=640\n";
-        verifyLogical(root, expectedLogical);
-        verifyResult(root, expectedResult);
-
-        String expectedSparkSql =
-                "SELECT `ENAME`, `TOSTRING`('1600', 'hex') `salary_hex`\nFROM `scott`.`EMP`\nLIMIT 1";
-        verifyPPLToSparkSQL(root, expectedSparkSql);
-    }
-
-    @Test
-    public void testToStringCommaFromNumberAsString() {
-        String ppl =
-                "source=EMP |  eval salary_comma = tostring(\"160040222\", \"commas\") | fields ENAME, salary_comma| head 1";
-        RelNode root = getRelNode(ppl);
-        String expectedLogical =
-                "LogicalSort(fetch=[1])\n  LogicalProject(ENAME=[$1], salary_comma=[TOSTRING('160040222':VARCHAR, 'commas':VARCHAR)])\n    LogicalTableScan(table=[[scott, EMP]])\n";
-        String expectedResult =
-                "ENAME=SMITH; salary_comma=160,040,222\n";
-        verifyLogical(root, expectedLogical);
-        verifyResult(root, expectedResult);
-
-        String expectedSparkSql =
-                "SELECT `ENAME`, `TOSTRING`('160040222', 'commas') `salary_comma`\nFROM `scott`.`EMP`\nLIMIT 1";
-        verifyPPLToSparkSQL(root, expectedSparkSql);
-    }
-    @Test
-    public void testToStringBinaryFromNumberAsString() {
-        String ppl =
-                "source=EMP |  eval salary_binary = tostring(\"160040222\", \"binary\") | fields ENAME, salary_binary| head 1";
-        RelNode root = getRelNode(ppl);
-        String expectedLogical =
-                "LogicalSort(fetch=[1])\n  LogicalProject(ENAME=[$1], salary_binary=[TOSTRING('160040222':VARCHAR, 'binary':VARCHAR)])\n    LogicalTableScan(table=[[scott, EMP]])\n";
-        String expectedResult =
-                "ENAME=SMITH; salary_binary=1001100010100000010100011110\n";
-        verifyLogical(root, expectedLogical);
-        verifyResult(root, expectedResult);
-
-        String expectedSparkSql =
-                "SELECT `ENAME`, `TOSTRING`('160040222', 'binary') `salary_binary`\nFROM `scott`.`EMP`\nLIMIT 1";
-        verifyPPLToSparkSQL(root, expectedSparkSql);
-    }
-    @Test
+  @Test
+  public void testToStringHexFromNumberAsString() {
+    String ppl =
+        "source=EMP |  eval salary_hex = tostring(\"1600\", \"hex\") | fields ENAME, salary_hex|"
+            + " head 1";
+    RelNode root = getRelNode(ppl);
+    String expectedLogical =
+        "LogicalSort(fetch=[1])\n"
+            + "  LogicalProject(ENAME=[$1], salary_hex=[TOSTRING('1600':VARCHAR, 'hex':VARCHAR)])\n"
+            + "    LogicalTableScan(table=[[scott, EMP]])\n";
+    String expectedResult = "ENAME=SMITH; salary_hex=640\n";
+    verifyLogical(root, expectedLogical);
+    verifyResult(root, expectedResult);
+
+    String expectedSparkSql =
+        "SELECT `ENAME`, `TOSTRING`('1600', 'hex') `salary_hex`\nFROM `scott`.`EMP`\nLIMIT 1";
+    verifyPPLToSparkSQL(root, expectedSparkSql);
+  }
+
+  @Test
+  public void testToStringCommaFromNumberAsString() {
+    String ppl =
+        "source=EMP |  eval salary_comma = tostring(\"160040222\", \"commas\") | fields ENAME,"
+            + " salary_comma| head 1";
+    RelNode root = getRelNode(ppl);
+    String expectedLogical =
+        "LogicalSort(fetch=[1])\n"
+            + "  LogicalProject(ENAME=[$1], salary_comma=[TOSTRING('160040222':VARCHAR,"
+            + " 'commas':VARCHAR)])\n"
+            + "    LogicalTableScan(table=[[scott, EMP]])\n";
+    String expectedResult = "ENAME=SMITH; salary_comma=160,040,222\n";
+    verifyLogical(root, expectedLogical);
+    verifyResult(root, expectedResult);
+
+    String expectedSparkSql =
+        "SELECT `ENAME`, `TOSTRING`('160040222', 'commas') `salary_comma`\n"
+            + "FROM `scott`.`EMP`\n"
+            + "LIMIT 1";
+    verifyPPLToSparkSQL(root, expectedSparkSql);
+  }
+
+  @Test
+  public void testToStringBinaryFromNumberAsString() {
+    String ppl =
+        "source=EMP |  eval salary_binary = tostring(\"160040222\", \"binary\") | fields ENAME,"
+            + " salary_binary| head 1";
+    RelNode root = getRelNode(ppl);
+    String expectedLogical =
+        "LogicalSort(fetch=[1])\n"
+            + "  LogicalProject(ENAME=[$1], salary_binary=[TOSTRING('160040222':VARCHAR,"
+            + " 'binary':VARCHAR)])\n"
+            + "    LogicalTableScan(table=[[scott, EMP]])\n";
+    String expectedResult = "ENAME=SMITH; salary_binary=1001100010100000010100011110\n";
+    verifyLogical(root, expectedLogical);
+    verifyResult(root, expectedResult);
+
+    String expectedSparkSql =
+        "SELECT `ENAME`, `TOSTRING`('160040222', 'binary') `salary_binary`\n"
+            + "FROM `scott`.`EMP`\n"
+            + "LIMIT 1";
+    verifyPPLToSparkSQL(root, expectedSparkSql);
+  }
+
+  @Test
   public void testToStringCommas() {
     String ppl =
         "source=EMP |  eval salary_commas = tostring(SAL, \"commas\") | fields ENAME,"

From 6e24aa3c4b16f6a5734db18f210b8b5c1f5f245f Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Fri, 17 Oct 2025 13:32:18 -0700
Subject: [PATCH 11/33] added doc update to specifically set 2nd argument as
 optional

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 docs/user/ppl/functions/conversion.rst | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/docs/user/ppl/functions/conversion.rst b/docs/user/ppl/functions/conversion.rst
index 036a89daf00..9f9646efef4 100644
--- a/docs/user/ppl/functions/conversion.rst
+++ b/docs/user/ppl/functions/conversion.rst
@@ -86,10 +86,10 @@ Description
 >>>>>>>>>>>
 The following usage options are available, depending on the parameter types and the number of parameters.
 
-Usage with format type: tostring(ANY, [format]): Converts the number in first argument  to provided format type string in second argument. If non number type, then it converts to default string representation.
+Usage with format type: tostring(ANY, [format]): Converts the number in first argument  to provided format type string in second argument. If second argument is not provided, then it converts to default string representation.
 Return type: string
 
-Usage for boolean parameter without format type tostring(boolean): Converts the string to 'True' or 'False'.
+Usage for boolean parameter without format type tostring(boolean): Converts the string to 'TRUE' or 'FALSE'.
 Return type: string
 
 You can use this function with the eval commands and as part of eval expressions. If first argument can be any valid type , second argument is optional and if provided , it needs to be format name to convert to where first argument contains only numbers. If first argument is boolean, then second argument is not used even if its provided.
@@ -100,12 +100,13 @@ a) "binary" Converts a number to a binary value.
 b) "hex" Converts the number to a hexadecimal value.
 c) "commas" Formats the number with commas. If the number includes a decimal, the function rounds the number to nearest two decimal places.
 d) "duration" Converts the value in seconds to the readable time format HH:MM:SS.
+5) "duration_millis" Converts the value in milliseconds to the readable time format HH:MM:SS.
 
 The format argument is optional and is only used when the value argument is a number. The tostring function supports the following formats.
 
 Basic examples:
 
-The following example returns "True 0xF 12,345.68".
+The following example returns "TRUE 0xF 12,345.68".
 
     ... | eval n=tostring(1==1) + " " + tostring(15, "hex") + " " + tostring(12345.6789, "commas")
 
@@ -169,5 +170,5 @@ Example::
     +---------------------+
     | boolean_str         |
     |---------------------+
-    | True                |
+    | TRUE                |
     +---------------------+
\ No newline at end of file

From 454cfc8db324866376f2452290b0fd0739008754 Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Fri, 17 Oct 2025 13:33:59 -0700
Subject: [PATCH 12/33] mentioned as value instead of number specifically

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 docs/user/ppl/functions/conversion.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/docs/user/ppl/functions/conversion.rst b/docs/user/ppl/functions/conversion.rst
index 9f9646efef4..4f2d432c71a 100644
--- a/docs/user/ppl/functions/conversion.rst
+++ b/docs/user/ppl/functions/conversion.rst
@@ -86,7 +86,7 @@ Description
 >>>>>>>>>>>
 The following usage options are available, depending on the parameter types and the number of parameters.
 
-Usage with format type: tostring(ANY, [format]): Converts the number in first argument  to provided format type string in second argument. If second argument is not provided, then it converts to default string representation.
+Usage with format type: tostring(ANY, [format]): Converts the value in first argument  to provided format type string in second argument. If second argument is not provided, then it converts to default string representation.
 Return type: string
 
 Usage for boolean parameter without format type tostring(boolean): Converts the string to 'TRUE' or 'FALSE'.

From b221e8c4f583b947198253ee90b5edb6f15b382a Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Fri, 17 Oct 2025 13:46:56 -0700
Subject: [PATCH 13/33] fixed wrong bullet point

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 docs/user/ppl/functions/conversion.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/docs/user/ppl/functions/conversion.rst b/docs/user/ppl/functions/conversion.rst
index 4f2d432c71a..708bde1fa11 100644
--- a/docs/user/ppl/functions/conversion.rst
+++ b/docs/user/ppl/functions/conversion.rst
@@ -100,7 +100,7 @@ a) "binary" Converts a number to a binary value.
 b) "hex" Converts the number to a hexadecimal value.
 c) "commas" Formats the number with commas. If the number includes a decimal, the function rounds the number to nearest two decimal places.
 d) "duration" Converts the value in seconds to the readable time format HH:MM:SS.
-5) "duration_millis" Converts the value in milliseconds to the readable time format HH:MM:SS.
+e) "duration_millis" Converts the value in milliseconds to the readable time format HH:MM:SS.
 
 The format argument is optional and is only used when the value argument is a number. The tostring function supports the following formats.
 

From ea9ba0fa8b5b63053df344930dc218e83dc75f91 Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Mon, 20 Oct 2025 12:41:39 -0700
Subject: [PATCH 14/33] added more unit tests

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 .../function/udf/ToNumberFunctionTest.java    | 192 ++++++++++++++++++
 1 file changed, 192 insertions(+)
 create mode 100644 core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java

diff --git a/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java b/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java
new file mode 100644
index 00000000000..d7f2b6fd685
--- /dev/null
+++ b/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java
@@ -0,0 +1,192 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.sql.expression.function.udf;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.math.BigDecimal;
+import java.util.Locale;
+import org.apache.calcite.sql.type.ReturnTypes;
+import org.junit.jupiter.api.Test;
+import org.opensearch.sql.calcite.utils.PPLOperandTypes;
+
+public class ToNumberFunctionTest {
+
+  private final ToNumberFunction function = new ToNumberFunction();
+
+  @Test
+  void testGetReturnTypeInference() {
+    assertEquals(ReturnTypes.DOUBLE_FORCE_NULLABLE, function.getReturnTypeInference());
+  }
+
+  @Test
+  void testGetOperandMetadata() {
+    assertEquals(PPLOperandTypes.STRING_OR_STRING_INTEGER, function.getOperandMetadata());
+  }
+
+  @Test
+  void testToNumberWithDefaultBase() {
+    assertEquals(123, ToNumberFunction.toNumber("123"));
+    assertEquals(0, ToNumberFunction.toNumber("0"));
+    assertEquals(-456, ToNumberFunction.toNumber("-456"));
+    assertEquals(123.45, ToNumberFunction.toNumber("123.45"));
+    assertEquals(-123.45, ToNumberFunction.toNumber("-123.45"));
+    assertEquals(0.5, ToNumberFunction.toNumber("0.5"));
+    assertEquals(-0.5, ToNumberFunction.toNumber("-0.5"));
+  }
+
+  @Test
+  void testToNumberWithBase10() {
+    assertEquals(123, ToNumberFunction.toNumber("123", 10));
+    assertEquals(0, ToNumberFunction.toNumber("0", 10));
+    assertEquals(-456, ToNumberFunction.toNumber("-456", 10));
+    assertEquals(123.45, ToNumberFunction.toNumber("123.45", 10));
+    assertEquals(-123.45, ToNumberFunction.toNumber("-123.45", 10));
+  }
+
+  @Test
+  void testToNumberWithBase2() {
+    assertEquals(5, ToNumberFunction.toNumber("101", 2));
+    assertEquals(0, ToNumberFunction.toNumber("0", 2));
+    assertEquals(1, ToNumberFunction.toNumber("1", 2));
+    assertEquals(7, ToNumberFunction.toNumber("111", 2));
+    assertEquals(10, ToNumberFunction.toNumber("1010", 2));
+  }
+
+  @Test
+  void testToNumberWithBase8() {
+    assertEquals(64, ToNumberFunction.toNumber("100", 8));
+    assertEquals(8, ToNumberFunction.toNumber("10", 8));
+    assertEquals(83, ToNumberFunction.toNumber("123", 8));
+    assertEquals(511, ToNumberFunction.toNumber("777", 8));
+  }
+
+  @Test
+  void testToNumberWithBase16() {
+    assertEquals(255, ToNumberFunction.toNumber("FF", 16));
+    assertEquals(16, ToNumberFunction.toNumber("10", 16));
+    assertEquals(171, ToNumberFunction.toNumber("AB", 16));
+    assertEquals(291, ToNumberFunction.toNumber("123", 16));
+    assertEquals(4095, ToNumberFunction.toNumber("FFF", 16));
+  }
+
+  @Test
+  void testToNumberWithBase36() {
+    assertEquals(35, ToNumberFunction.toNumber("Z", 36));
+    assertEquals(1295, ToNumberFunction.toNumber("ZZ", 36));
+    assertEquals(46655, ToNumberFunction.toNumber("ZZZ", 36));
+  }
+
+  @Test
+  void testToNumberWithDecimalBase2() {
+    assertEquals(2.5, ToNumberFunction.toNumber("10.1", 2));
+    assertEquals(1.5, ToNumberFunction.toNumber("1.1", 2));
+    assertEquals(3.75, ToNumberFunction.toNumber("11.11", 2));
+  }
+
+  @Test
+  void testToNumberWithDecimalBase16() {
+    assertEquals(255.5, ToNumberFunction.toNumber("FF.8", 16));
+    assertEquals(16.25, ToNumberFunction.toNumber("10.4", 16));
+    assertEquals(171.6875, ToNumberFunction.toNumber("AB.B", 16));
+  }
+
+  @Test
+  void testToNumberWithNegativeDecimal() {
+    assertEquals(-2.5, ToNumberFunction.toNumber("-10.1", 2));
+    assertEquals(-255.5, ToNumberFunction.toNumber("-FF.8", 16));
+    assertEquals(-123.45, ToNumberFunction.toNumber("-123.45", 10));
+  }
+
+  @Test
+  void testToNumberWithEmptyFractionalPart() {
+    assertEquals(123.0, ToNumberFunction.toNumber("123.", 10));
+    assertEquals(255.0, ToNumberFunction.toNumber("FF.", 16));
+    assertEquals(5.0, ToNumberFunction.toNumber("101.", 2));
+  }
+
+  @Test
+  void testToNumberWithZeroIntegerPart() {
+    assertEquals(0.5, ToNumberFunction.toNumber("0.5", 10));
+    assertEquals(0.5, ToNumberFunction.toNumber("0.1", 2));
+  }
+
+  @Test
+  void testToNumberInvalidBase() {
+    assertThrows(IllegalArgumentException.class, () -> {
+      ToNumberFunction.toNumber("123", 1);
+    });
+    
+    assertThrows(IllegalArgumentException.class, () -> {
+      ToNumberFunction.toNumber("123", 37);
+    });
+    
+    assertThrows(IllegalArgumentException.class, () -> {
+      ToNumberFunction.toNumber("123", 0);
+    });
+    
+    assertThrows(IllegalArgumentException.class, () -> {
+      ToNumberFunction.toNumber("123", -1);
+    });
+  }
+
+  @Test
+  void testToNumberInvalidDigits() {
+    assertThrows(IllegalArgumentException.class, () -> {
+      ToNumberFunction.toNumber("12A", 10);
+    });
+    
+    assertThrows(IllegalArgumentException.class, () -> {
+      ToNumberFunction.toNumber("102", 2);
+    });
+    
+    assertThrows(IllegalArgumentException.class, () -> {
+      ToNumberFunction.toNumber("189", 8);
+    });
+    
+    assertThrows(IllegalArgumentException.class, () -> {
+      ToNumberFunction.toNumber("GHI", 16);
+    });
+  }
+
+  @Test
+  void testToNumberInvalidFractionalDigits() {
+    assertThrows(IllegalArgumentException.class, () -> {
+      ToNumberFunction.toNumber("10.2", 2);
+    });
+    
+    assertThrows(IllegalArgumentException.class, () -> {
+      ToNumberFunction.toNumber("FF.G", 16);
+    });
+    
+    assertThrows(IllegalArgumentException.class, () -> {
+      ToNumberFunction.toNumber("123.ABC", 10);
+    });
+  }
+
+  @Test
+  void testToNumberEdgeCases() {
+    assertEquals(0, ToNumberFunction.toNumber("0", 2));
+    assertEquals(0, ToNumberFunction.toNumber("0", 36));
+    assertEquals(0.0, ToNumberFunction.toNumber("0.0", 10));
+    assertEquals(0.0, ToNumberFunction.toNumber("0.000", 10));
+  }
+
+  @Test
+  void testToNumberLargeNumbers() {
+    assertEquals(Integer.MAX_VALUE, ToNumberFunction.toNumber(String.valueOf(Integer.MAX_VALUE), 10));
+    assertEquals(Integer.MIN_VALUE, ToNumberFunction.toNumber(String.valueOf(Integer.MIN_VALUE), 10));
+  }
+
+  @Test
+  void testToNumberCaseInsensitivity() {
+    assertEquals(255, ToNumberFunction.toNumber("ff", 16));
+    assertEquals(255, ToNumberFunction.toNumber("FF", 16));
+    assertEquals(255, ToNumberFunction.toNumber("fF", 16));
+    assertEquals(171, ToNumberFunction.toNumber("ab", 16));
+    assertEquals(171, ToNumberFunction.toNumber("AB", 16));
+  }
+}

From 370b9bc5d30ec90fbd7dc668ca5ee0939a720f87 Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Tue, 21 Oct 2025 21:03:42 -0700
Subject: [PATCH 15/33] Update docs/user/ppl/functions/conversion.rst

Co-authored-by: ritvibhatt <53196324+ritvibhatt@users.noreply.github.com>
Signed-off-by: Asif Bashar <abashar@apple.com>
Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 docs/user/ppl/functions/conversion.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/docs/user/ppl/functions/conversion.rst b/docs/user/ppl/functions/conversion.rst
index fad37c0bf26..d9da1bf3d8e 100644
--- a/docs/user/ppl/functions/conversion.rst
+++ b/docs/user/ppl/functions/conversion.rst
@@ -86,7 +86,7 @@ Description
 >>>>>>>>>>>
 The following usage options are available, depending on the parameter types and the number of parameters.
 
-Usage with format type: tonumber(string, [base]): Converts the value in first argument  to provided base type string in second argument. If second argument is not provided, then it converts to base 10 number representation.
+Usage: tonumber(string, [base]) converts the value in first argument to provided base type string in second argument. If second argument is not provided, then it converts to base 10 number representation.
 Return type: Number
 
 

From f0706849c4446e47615a2228debbea69c069d0b0 Mon Sep 17 00:00:00 2001
From: Asif Bashar <abashar@apple.com>
Date: Tue, 21 Oct 2025 21:20:00 -0700
Subject: [PATCH 16/33] fix per recommendation

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 docs/user/ppl/functions/conversion.rst        | 34 ++++++++-----------
 ppl/src/main/antlr/OpenSearchPPLParser.g4     |  4 +--
 .../sql/ppl/parser/AstExpressionBuilder.java  | 32 -----------------
 3 files changed, 16 insertions(+), 54 deletions(-)

diff --git a/docs/user/ppl/functions/conversion.rst b/docs/user/ppl/functions/conversion.rst
index d9da1bf3d8e..3264d422ce1 100644
--- a/docs/user/ppl/functions/conversion.rst
+++ b/docs/user/ppl/functions/conversion.rst
@@ -84,39 +84,34 @@ TONUMBER
 
 Description
 >>>>>>>>>>>
+
 The following usage options are available, depending on the parameter types and the number of parameters.
 
 Usage: tonumber(string, [base]) converts the value in first argument to provided base type string in second argument. If second argument is not provided, then it converts to base 10 number representation.
+
 Return type: Number
 
 
 You can use this function with the eval commands and as part of eval expressions.
 Base values can be between 2 and 36.
 
-
-
-Basic examples:
 You can use this function to convert a string representation of a binary number to return the corresponding number in base 10.
 
-For example, the result of the following function is 5:
-eval result = tonumber("0101", 2)
-
+Following example converts a string in binary to the number representation::
 
-Example::
-Following example converts a string in binary to the number representation.
-    os> source=EMP | eval int_value = tonumber('010101',2) | fields int_value|head 1
+    os> source=EMP | eval int_value = tonumber('010101',2) | fields int_value | head 1
     fetched rows / total rows = 1/1
-    +--------------+
-    | int_value    |
-    |--------------+
-    | 21.0         |
-    +--------------+
+    +---------------+
+    |  int_value    |
+    |---------------+
+    |  21.0         |
+    +---------------+
+
 
+Following example converts a string in hex to the number representation::
 
-Following example converts a string in hex to the number representation.
-Example::
 
-    os> source=EMP | eval int_value = tonumber('FA34',16) | fields int_value|head 1
+    os> source=EMP | eval int_value = tonumber('FA34',16) | fields int_value | head 1
     fetched rows / total rows = 1/1
     +---------------+
     | int_value     |
@@ -124,10 +119,9 @@ Example::
     | 64052.0       |
     +---------------+
 
-Following example converts a string in decimal  to the number representation.
-Example::
+Following example converts a string in decimal  to the number representation::
 
-     os> source=EMP | eval int_value = tonumber('4598') | fields int_value|head 1
+     os> source=EMP | eval int_value = tonumber('4598') | fields int_value | head 1
      fetched rows / total rows = 1/1
     +---------------+
     | int_value     |
diff --git a/ppl/src/main/antlr/OpenSearchPPLParser.g4 b/ppl/src/main/antlr/OpenSearchPPLParser.g4
index e974c303375..a26b7381797 100644
--- a/ppl/src/main/antlr/OpenSearchPPLParser.g4
+++ b/ppl/src/main/antlr/OpenSearchPPLParser.g4
@@ -848,10 +848,9 @@ evalFunctionCall
    ;
 
 
-// cast, tostring function
+// cast function
 dataTypeFunctionCall
    : CAST LT_PRTHS logicalExpression AS convertedDataType RT_PRTHS
-   | TONUMBER LT_PRTHS functionArgs RT_PRTHS
    ;
 
 
@@ -1234,6 +1233,7 @@ textFunctionName
    | LOCATE
    | REPLACE
    | REVERSE
+   | TONUMBER
    ;
 
 positionFunctionName
diff --git a/ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java b/ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java
index 244f287c77a..b70226d039a 100644
--- a/ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java
+++ b/ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java
@@ -431,39 +431,7 @@ public DataTypeFunctionCallContext createDataTypeFunctionCallContext(String cast
   /** Cast function. */
   @Override
   public UnresolvedExpression visitDataTypeFunctionCall(DataTypeFunctionCallContext ctx) {
-    if (ctx.functionArgs() != null) {
-
-      ParseTree rootNode = ctx.getChild(0);
-      String functionName = rootNode.getText();
-      final String mappedName =
-          FUNCTION_NAME_MAPPING.getOrDefault(functionName.toLowerCase(Locale.ROOT), functionName);
-      System.out.println(mappedName);
-      if (mappedName != null && mappedName.equals("tostring")) {
-        if (ctx.functionArgs().functionArg().size() == 1) {
-          List<OpenSearchPPLParser.FunctionArgContext> functionArgs =
-              ctx.functionArgs().functionArg();
-
-          String castExpresstion =
-              String.format("cast( %s as String)", functionArgs.getFirst().getText());
-          DataTypeFunctionCallContext toStringDataTypeConversionContext =
-              this.createDataTypeFunctionCallContext(castExpresstion);
-          return new Cast(
-              visit(toStringDataTypeConversionContext.logicalExpression()),
-              visit(toStringDataTypeConversionContext.convertedDataType()));
-          //
-        } else {
-          return buildFunction(mappedName, ctx.functionArgs().functionArg());
-        }
-      } else if (mappedName != null && mappedName.equals("tonumber")) {
-
-          return buildFunction(mappedName, ctx.functionArgs().functionArg());
-
-      }  else {
-        return new Cast(visit(ctx.logicalExpression()), visit(ctx.convertedDataType()));
-      }
-    } else {
       return new Cast(visit(ctx.logicalExpression()), visit(ctx.convertedDataType()));
-    }
   }
 
   @Override

From a2accf5bc8caa7ad804fba592cc15954dc8fbd28 Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Tue, 21 Oct 2025 21:33:51 -0700
Subject: [PATCH 17/33] updated recommended changes

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 .../function/PPLBuiltinOperators.java         |   9 +-
 .../expression/function/PPLFuncImpTable.java  | 226 +++++++++++++++++-
 2 files changed, 233 insertions(+), 2 deletions(-)

diff --git a/core/src/main/java/org/opensearch/sql/expression/function/PPLBuiltinOperators.java b/core/src/main/java/org/opensearch/sql/expression/function/PPLBuiltinOperators.java
index 14f82947c74..7fd768a8d8b 100644
--- a/core/src/main/java/org/opensearch/sql/expression/function/PPLBuiltinOperators.java
+++ b/core/src/main/java/org/opensearch/sql/expression/function/PPLBuiltinOperators.java
@@ -60,7 +60,14 @@
 import org.opensearch.sql.expression.function.jsonUDF.JsonFunctionImpl;
 import org.opensearch.sql.expression.function.jsonUDF.JsonKeysFunctionImpl;
 import org.opensearch.sql.expression.function.jsonUDF.JsonSetFunctionImpl;
-import org.opensearch.sql.expression.function.udf.*;
+import org.opensearch.sql.expression.function.udf.CryptographicFunction;
+import org.opensearch.sql.expression.function.udf.ParseFunction;
+import org.opensearch.sql.expression.function.udf.RelevanceQueryFunction;
+import org.opensearch.sql.expression.function.udf.RexExtractFunction;
+import org.opensearch.sql.expression.function.udf.RexExtractMultiFunction;
+import org.opensearch.sql.expression.function.udf.RexOffsetFunction;
+import org.opensearch.sql.expression.function.udf.SpanFunction;
+import org.opensearch.sql.expression.function.udf.ToNumberFunction;
 import org.opensearch.sql.expression.function.udf.condition.EarliestFunction;
 import org.opensearch.sql.expression.function.udf.condition.EnhancedCoalesceFunction;
 import org.opensearch.sql.expression.function.udf.condition.LatestFunction;
diff --git a/core/src/main/java/org/opensearch/sql/expression/function/PPLFuncImpTable.java b/core/src/main/java/org/opensearch/sql/expression/function/PPLFuncImpTable.java
index 6f61eb14b48..d9e594f089f 100644
--- a/core/src/main/java/org/opensearch/sql/expression/function/PPLFuncImpTable.java
+++ b/core/src/main/java/org/opensearch/sql/expression/function/PPLFuncImpTable.java
@@ -8,7 +8,231 @@
 import static org.apache.calcite.sql.SqlJsonConstructorNullClause.NULL_ON_NULL;
 import static org.opensearch.sql.calcite.utils.OpenSearchTypeFactory.TYPE_FACTORY;
 import static org.opensearch.sql.calcite.utils.OpenSearchTypeFactory.getLegacyTypeName;
-import static org.opensearch.sql.expression.function.BuiltinFunctionName.*;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.ABS;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.ACOS;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.ADD;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.ADDDATE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.ADDFUNCTION;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.ADDTIME;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.AND;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.ARRAY;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.ARRAY_LENGTH;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.ASCII;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.ASIN;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.ATAN;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.ATAN2;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.AVG;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.CBRT;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.CEIL;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.CEILING;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.CIDRMATCH;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.COALESCE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.CONCAT;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.CONCAT_WS;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.CONV;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.CONVERT_TZ;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.COS;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.COSH;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.COT;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.COUNT;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.CRC32;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.CURDATE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.CURRENT_DATE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.CURRENT_TIME;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.CURRENT_TIMESTAMP;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.CURTIME;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.DATE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.DATEDIFF;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.DATETIME;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.DATE_ADD;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.DATE_FORMAT;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.DATE_SUB;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.DAY;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.DAYNAME;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.DAYOFMONTH;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.DAYOFWEEK;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.DAYOFYEAR;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.DAY_OF_MONTH;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.DAY_OF_WEEK;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.DAY_OF_YEAR;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.DEGREES;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.DIVIDE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.DIVIDEFUNCTION;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.E;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.EARLIEST;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.EQUAL;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.EXISTS;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.EXP;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.EXPM1;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.EXTRACT;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.FILTER;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.FIRST;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.FLOOR;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.FORALL;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.FROM_DAYS;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.FROM_UNIXTIME;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.GET_FORMAT;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.GREATER;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.GTE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.HOUR;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.HOUR_OF_DAY;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.IF;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.IFNULL;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.INTERNAL_GROK;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.INTERNAL_ITEM;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.INTERNAL_PARSE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.INTERNAL_PATTERN;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.INTERNAL_PATTERN_PARSER;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.INTERNAL_REGEXP_REPLACE_3;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.INTERNAL_REGEXP_REPLACE_5;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.INTERNAL_REGEXP_REPLACE_PG_4;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.INTERNAL_TRANSLATE3;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.IS_BLANK;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.IS_EMPTY;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.IS_NOT_NULL;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.IS_NULL;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.IS_PRESENT;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.JSON;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.JSON_APPEND;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.JSON_ARRAY;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.JSON_ARRAY_LENGTH;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.JSON_DELETE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.JSON_EXTEND;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.JSON_EXTRACT;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.JSON_EXTRACT_ALL;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.JSON_KEYS;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.JSON_OBJECT;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.JSON_SET;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.JSON_VALID;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.LAST;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.LAST_DAY;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.LATEST;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.LEFT;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.LENGTH;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.LESS;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.LIKE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.LIST;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.LN;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.LOCALTIME;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.LOCALTIMESTAMP;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.LOCATE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.LOG;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.LOG10;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.LOG2;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.LOWER;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.LTE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.LTRIM;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MAKEDATE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MAKETIME;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MAP_APPEND;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MAP_CONCAT;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MAP_REMOVE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MATCH;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MATCH_BOOL_PREFIX;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MATCH_PHRASE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MATCH_PHRASE_PREFIX;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MAX;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MD5;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MEDIAN;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MICROSECOND;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MIN;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MINUTE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MINUTE_OF_DAY;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MINUTE_OF_HOUR;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MOD;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MODULUS;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MODULUSFUNCTION;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MONTH;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MONTHNAME;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MONTH_OF_YEAR;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MULTIPLY;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MULTIPLYFUNCTION;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MULTI_MATCH;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MVAPPEND;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.MVJOIN;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.NOT;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.NOTEQUAL;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.NOW;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.NULLIF;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.OR;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.PERCENTILE_APPROX;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.PERIOD_ADD;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.PERIOD_DIFF;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.PI;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.POSITION;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.POW;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.POWER;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.QUARTER;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.QUERY_STRING;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.RADIANS;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.RAND;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.REDUCE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.REGEXP;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.REGEX_MATCH;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.REPLACE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.REVERSE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.REX_EXTRACT;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.REX_EXTRACT_MULTI;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.REX_OFFSET;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.RIGHT;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.RINT;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.ROUND;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.RTRIM;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.SECOND;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.SECOND_OF_MINUTE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.SEC_TO_TIME;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.SHA1;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.SHA2;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.SIGN;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.SIGNUM;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.SIMPLE_QUERY_STRING;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.SIN;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.SINH;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.SPAN;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.SQRT;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.STDDEV_POP;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.STDDEV_SAMP;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.STRCMP;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.STRFTIME;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.STR_TO_DATE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.SUBDATE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.SUBSTR;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.SUBSTRING;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.SUBTIME;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.SUBTRACT;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.SUBTRACTFUNCTION;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.SUM;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.SYSDATE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.TAKE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.TIME;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.TIMEDIFF;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.TIMESTAMP;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.TIMESTAMPADD;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.TIMESTAMPDIFF;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.TIME_FORMAT;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.TIME_TO_SEC;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.TO_DAYS;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.TO_SECONDS;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.TRANSFORM;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.TRIM;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.TRUNCATE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.TYPEOF;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.UNIX_TIMESTAMP;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.UPPER;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.UTC_DATE;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.UTC_TIME;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.UTC_TIMESTAMP;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.VALUES;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.VARPOP;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.VARSAMP;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.WEEK;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.WEEKDAY;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.WEEKOFYEAR;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.WEEK_OF_YEAR;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.XOR;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.YEAR;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.YEARWEEK;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.TONUMBER;
 
 import com.google.common.collect.ImmutableMap;
 import java.math.BigDecimal;

From 3adda5d37467116c9e8b1591832755281361ce9e Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Tue, 21 Oct 2025 21:36:28 -0700
Subject: [PATCH 18/33] updated recommended changes

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 .../sql/ppl/parser/AstExpressionBuilder.java     | 16 +---------------
 1 file changed, 1 insertion(+), 15 deletions(-)

diff --git a/ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java b/ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java
index b70226d039a..f7f6b3e914a 100644
--- a/ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java
+++ b/ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java
@@ -414,24 +414,10 @@ private Function buildFunction(
         functionName, args.stream().map(this::visitFunctionArg).collect(Collectors.toList()));
   }
 
-  public DataTypeFunctionCallContext createDataTypeFunctionCallContext(String castExpression) {
-    // Create a case-insensitive character stream from the input
-    CaseInsensitiveCharStream charStream = new CaseInsensitiveCharStream(castExpression);
-
-    // Create lexer and parser
-    OpenSearchPPLLexer lexer = new OpenSearchPPLLexer(charStream);
-    CommonTokenStream tokens = new CommonTokenStream(lexer);
-    OpenSearchPPLParser parser = new OpenSearchPPLParser(tokens);
-
-    // Parse the expression - cast is part of evalFunctionCall
-    DataTypeFunctionCallContext evalContext = parser.dataTypeFunctionCall();
-    return evalContext;
-  }
-
   /** Cast function. */
   @Override
   public UnresolvedExpression visitDataTypeFunctionCall(DataTypeFunctionCallContext ctx) {
-      return new Cast(visit(ctx.logicalExpression()), visit(ctx.convertedDataType()));
+    return new Cast(visit(ctx.logicalExpression()), visit(ctx.convertedDataType()));
   }
 
   @Override

From 17b1d86c3098b1fa11171ffe05fdcaa47fbf53d8 Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Tue, 21 Oct 2025 21:38:11 -0700
Subject: [PATCH 19/33] updated recommended changes

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 .../org/opensearch/sql/ppl/parser/AstExpressionBuilder.java    | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java b/ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java
index f7f6b3e914a..f037376f5c2 100644
--- a/ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java
+++ b/ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java
@@ -19,7 +19,6 @@
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
 import java.util.stream.Stream;
-import org.antlr.v4.runtime.CommonTokenStream;
 import org.antlr.v4.runtime.ParserRuleContext;
 import org.antlr.v4.runtime.RuleContext;
 import org.antlr.v4.runtime.tree.ParseTree;
@@ -30,10 +29,8 @@
 import org.opensearch.sql.ast.expression.subquery.ScalarSubquery;
 import org.opensearch.sql.ast.tree.Trendline;
 import org.opensearch.sql.calcite.plan.OpenSearchConstants;
-import org.opensearch.sql.common.antlr.CaseInsensitiveCharStream;
 import org.opensearch.sql.common.antlr.SyntaxCheckException;
 import org.opensearch.sql.common.utils.StringUtils;
-import org.opensearch.sql.ppl.antlr.parser.OpenSearchPPLLexer;
 import org.opensearch.sql.ppl.antlr.parser.OpenSearchPPLParser;
 import org.opensearch.sql.ppl.antlr.parser.OpenSearchPPLParser.BinaryArithmeticContext;
 import org.opensearch.sql.ppl.antlr.parser.OpenSearchPPLParser.BooleanLiteralContext;

From eca7d139fce7d750e2be988facd8764dd6d1674c Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Tue, 21 Oct 2025 21:38:59 -0700
Subject: [PATCH 20/33] updated recommended changes

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 .../opensearch/sql/expression/function/BuiltinFunctionName.java  | 1 +
 1 file changed, 1 insertion(+)

diff --git a/core/src/main/java/org/opensearch/sql/expression/function/BuiltinFunctionName.java b/core/src/main/java/org/opensearch/sql/expression/function/BuiltinFunctionName.java
index fe862adc322..df3ae06d5c8 100644
--- a/core/src/main/java/org/opensearch/sql/expression/function/BuiltinFunctionName.java
+++ b/core/src/main/java/org/opensearch/sql/expression/function/BuiltinFunctionName.java
@@ -149,6 +149,7 @@ public enum BuiltinFunctionName {
   SYSDATE(FunctionName.of("sysdate")),
 
   /** Text Functions. */
+  TOSTRING(FunctionName.of("tostring")),
   TONUMBER(FunctionName.of("tonumber")),
 
   /** IP Functions. */

From e780c156df19215bc03e4ba45988b32393f6ddcc Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Tue, 21 Oct 2025 21:40:50 -0700
Subject: [PATCH 21/33] updated recommended changes

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 ppl/src/main/antlr/OpenSearchPPLParser.g4 | 2 --
 1 file changed, 2 deletions(-)

diff --git a/ppl/src/main/antlr/OpenSearchPPLParser.g4 b/ppl/src/main/antlr/OpenSearchPPLParser.g4
index a26b7381797..d386813fc96 100644
--- a/ppl/src/main/antlr/OpenSearchPPLParser.g4
+++ b/ppl/src/main/antlr/OpenSearchPPLParser.g4
@@ -847,13 +847,11 @@ evalFunctionCall
    : evalFunctionName LT_PRTHS functionArgs RT_PRTHS
    ;
 
-
 // cast function
 dataTypeFunctionCall
    : CAST LT_PRTHS logicalExpression AS convertedDataType RT_PRTHS
    ;
 
-
 convertedDataType
    : typeName = DATE
    | typeName = TIME

From e3884b0a5ac00d147268fe964dcf554739685c88 Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Tue, 21 Oct 2025 21:42:31 -0700
Subject: [PATCH 22/33] updated recommended changes

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 .../org/opensearch/sql/expression/function/PPLFuncImpTable.java  | 1 -
 1 file changed, 1 deletion(-)

diff --git a/core/src/main/java/org/opensearch/sql/expression/function/PPLFuncImpTable.java b/core/src/main/java/org/opensearch/sql/expression/function/PPLFuncImpTable.java
index d9e594f089f..a5d0d1b8712 100644
--- a/core/src/main/java/org/opensearch/sql/expression/function/PPLFuncImpTable.java
+++ b/core/src/main/java/org/opensearch/sql/expression/function/PPLFuncImpTable.java
@@ -1062,7 +1062,6 @@ void populate() {
                               SqlTypeFamily.INTEGER,
                               SqlTypeFamily.INTEGER)),
               false));
-
       register(
           LOG,
           (FunctionImp2)

From 042d3e821a03a2c5a5438f449bfbd983d8e53057 Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Wed, 22 Oct 2025 10:11:40 -0700
Subject: [PATCH 23/33] spotless apply

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 .../sql/calcite/utils/PPLOperandTypes.java    |  10 +-
 .../expression/function/PPLFuncImpTable.java  |   2 +-
 .../function/udf/ToNumberFunction.java        | 179 ++++++++----------
 .../function/udf/ToNumberFunctionTest.java    | 112 ++++++-----
 4 files changed, 153 insertions(+), 150 deletions(-)

diff --git a/core/src/main/java/org/opensearch/sql/calcite/utils/PPLOperandTypes.java b/core/src/main/java/org/opensearch/sql/calcite/utils/PPLOperandTypes.java
index b00fa607d55..c64fa6ef4d5 100644
--- a/core/src/main/java/org/opensearch/sql/calcite/utils/PPLOperandTypes.java
+++ b/core/src/main/java/org/opensearch/sql/calcite/utils/PPLOperandTypes.java
@@ -106,12 +106,12 @@ private PPLOperandTypes() {}
               SqlTypeFamily.CHARACTER, SqlTypeFamily.CHARACTER, SqlTypeFamily.INTEGER));
 
   public static final UDFOperandMetadata STRING_OR_STRING_INTEGER =
-            UDFOperandMetadata.wrap(
-                    (CompositeOperandTypeChecker)
-                    OperandTypes.family(SqlTypeFamily.CHARACTER).or(OperandTypes.family(SqlTypeFamily.CHARACTER, SqlTypeFamily.INTEGER)));
-
+      UDFOperandMetadata.wrap(
+          (CompositeOperandTypeChecker)
+              OperandTypes.family(SqlTypeFamily.CHARACTER)
+                  .or(OperandTypes.family(SqlTypeFamily.CHARACTER, SqlTypeFamily.INTEGER)));
 
-    public static final UDFOperandMetadata STRING_STRING_INTEGER_INTEGER =
+  public static final UDFOperandMetadata STRING_STRING_INTEGER_INTEGER =
       UDFOperandMetadata.wrap(
           OperandTypes.family(
               SqlTypeFamily.CHARACTER,
diff --git a/core/src/main/java/org/opensearch/sql/expression/function/PPLFuncImpTable.java b/core/src/main/java/org/opensearch/sql/expression/function/PPLFuncImpTable.java
index a5d0d1b8712..4339619275c 100644
--- a/core/src/main/java/org/opensearch/sql/expression/function/PPLFuncImpTable.java
+++ b/core/src/main/java/org/opensearch/sql/expression/function/PPLFuncImpTable.java
@@ -211,6 +211,7 @@
 import static org.opensearch.sql.expression.function.BuiltinFunctionName.TIMESTAMPDIFF;
 import static org.opensearch.sql.expression.function.BuiltinFunctionName.TIME_FORMAT;
 import static org.opensearch.sql.expression.function.BuiltinFunctionName.TIME_TO_SEC;
+import static org.opensearch.sql.expression.function.BuiltinFunctionName.TONUMBER;
 import static org.opensearch.sql.expression.function.BuiltinFunctionName.TO_DAYS;
 import static org.opensearch.sql.expression.function.BuiltinFunctionName.TO_SECONDS;
 import static org.opensearch.sql.expression.function.BuiltinFunctionName.TRANSFORM;
@@ -232,7 +233,6 @@
 import static org.opensearch.sql.expression.function.BuiltinFunctionName.XOR;
 import static org.opensearch.sql.expression.function.BuiltinFunctionName.YEAR;
 import static org.opensearch.sql.expression.function.BuiltinFunctionName.YEARWEEK;
-import static org.opensearch.sql.expression.function.BuiltinFunctionName.TONUMBER;
 
 import com.google.common.collect.ImmutableMap;
 import java.math.BigDecimal;
diff --git a/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java b/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java
index 95b37a0107c..0c5b576b297 100644
--- a/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java
+++ b/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java
@@ -5,12 +5,7 @@
 
 package org.opensearch.sql.expression.function.udf;
 
-import java.math.BigDecimal;
-import java.math.BigInteger;
-import java.text.NumberFormat;
 import java.util.List;
-import java.util.Locale;
-
 import org.apache.calcite.adapter.enumerable.NotNullImplementor;
 import org.apache.calcite.adapter.enumerable.NullPolicy;
 import org.apache.calcite.adapter.enumerable.RexToLixTranslator;
@@ -22,7 +17,6 @@
 import org.apache.calcite.sql.type.ReturnTypes;
 import org.apache.calcite.sql.type.SqlReturnTypeInference;
 import org.opensearch.sql.calcite.utils.PPLOperandTypes;
-import org.opensearch.sql.calcite.utils.PPLReturnTypes;
 import org.opensearch.sql.expression.function.ImplementorUDF;
 import org.opensearch.sql.expression.function.UDFOperandMetadata;
 
@@ -36,105 +30,92 @@
  * HH:MM:SS. if not format parameter provided, then consider value as boolean
  */
 public class ToNumberFunction extends ImplementorUDF {
-    public ToNumberFunction() {
-        super(
-                new org.opensearch.sql.expression.function.udf.ToNumberFunction.ToNumberImplementor(),
-                NullPolicy.ANY);
-    }
-
-    public static final String DURATION_FORMAT = "duration";
-    public static final String DURATION_MILLIS_FORMAT = "duration_millis";
-    public static final String HEX_FORMAT = "hex";
-    public static final String COMMAS_FORMAT = "commas";
-    public static final String BINARY_FORMAT = "binary";
-    public static final SqlFunctions.DateFormatFunction dateTimeFormatter =
-            new SqlFunctions.DateFormatFunction();
-    public static final String format24hour = "%H:%M:%S"; // 24-hour format
+  public ToNumberFunction() {
+    super(
+        new org.opensearch.sql.expression.function.udf.ToNumberFunction.ToNumberImplementor(),
+        NullPolicy.ANY);
+  }
+
+  public static final String DURATION_FORMAT = "duration";
+  public static final String DURATION_MILLIS_FORMAT = "duration_millis";
+  public static final String HEX_FORMAT = "hex";
+  public static final String COMMAS_FORMAT = "commas";
+  public static final String BINARY_FORMAT = "binary";
+  public static final SqlFunctions.DateFormatFunction dateTimeFormatter =
+      new SqlFunctions.DateFormatFunction();
+  public static final String format24hour = "%H:%M:%S"; // 24-hour format
+
+  @Override
+  public SqlReturnTypeInference getReturnTypeInference() {
+    return ReturnTypes.DOUBLE_FORCE_NULLABLE;
+  }
+
+  @Override
+  public UDFOperandMetadata getOperandMetadata() {
+    return PPLOperandTypes.STRING_OR_STRING_INTEGER;
+  }
+
+  public static class ToNumberImplementor implements NotNullImplementor {
 
     @Override
-    public SqlReturnTypeInference getReturnTypeInference() {
-        return ReturnTypes.DOUBLE_FORCE_NULLABLE;
+    public Expression implement(
+        RexToLixTranslator translator, RexCall call, List<Expression> translatedOperands) {
+      Expression fieldValue = translatedOperands.get(0);
+      int base = 10;
+      if (translatedOperands.size() > 1) {
+        Expression baseExpr = translatedOperands.get(1);
+        return Expressions.call(ToNumberFunction.class, "toNumber", fieldValue, baseExpr);
+      } else {
+        return Expressions.call(ToNumberFunction.class, "toNumber", fieldValue);
+      }
     }
+  }
 
-    @Override
-    public UDFOperandMetadata getOperandMetadata() {
-        return PPLOperandTypes.STRING_OR_STRING_INTEGER;
-    }
-
-    public static class ToNumberImplementor implements NotNullImplementor {
-
-        @Override
-        public Expression implement(
-                RexToLixTranslator translator, RexCall call, List<Expression> translatedOperands) {
-            Expression fieldValue = translatedOperands.get(0);
-            int base = 10;
-            if (translatedOperands.size() > 1) {
-                Expression baseExpr = translatedOperands.get(1);
-                return Expressions.call(ToNumberFunction.class, "toNumber", fieldValue, baseExpr);
-            } else {
-                return Expressions.call(ToNumberFunction.class, "toNumber", fieldValue);
-            }
-
-
+  @Strict
+  public static Number toNumber(String numStr) {
+    return toNumber(numStr, 10);
+  }
 
-
-
-        }
+  @Strict
+  public static Number toNumber(String numStr, int base) {
+    if (base < 2 || base > 36) {
+      throw new IllegalArgumentException("Base must be between 2 and 36");
     }
 
-    @Strict
-    public static Number toNumber(String numStr) {
-        return toNumber(numStr, 10);
+    if (numStr.contains(".")) {
+
+      boolean isNegative = numStr.startsWith("-");
+      if (isNegative) {
+        numStr = numStr.substring(1);
+      }
+
+      // Split integer and fractional parts
+      String[] parts = numStr.split("\\.");
+      String intPart = parts[0];
+      String fracPart = parts.length > 1 ? parts[1] : "";
+
+      // Convert integer part
+      double intValue = 0;
+      for (char c : intPart.toCharArray()) {
+        int digit = Character.digit(c, base);
+        if (digit < 0) throw new IllegalArgumentException("Invalid digit: " + c);
+        intValue = intValue * base + digit;
+      }
+
+      // Convert fractional part
+      double fracValue = 0;
+      double divisor = base;
+      for (char c : fracPart.toCharArray()) {
+        int digit = Character.digit(c, base);
+        if (digit < 0) throw new IllegalArgumentException("Invalid digit: " + c);
+        fracValue += (double) digit / divisor;
+        divisor *= base;
+      }
+
+      double result = intValue + fracValue;
+      return isNegative ? -result : result;
+    } else {
+      return Integer.parseInt(numStr, base);
     }
-
-    @Strict
-    public static Number toNumber(String numStr, int base) {
-        if (base < 2 || base > 36) {
-            throw new IllegalArgumentException("Base must be between 2 and 36");
-        }
-
-        if (numStr.contains(".")) {
-
-
-            boolean isNegative = numStr.startsWith("-");
-            if (isNegative) {
-                numStr = numStr.substring(1);
-            }
-
-            // Split integer and fractional parts
-            String[] parts = numStr.split("\\.");
-            String intPart = parts[0];
-            String fracPart = parts.length > 1 ? parts[1] : "";
-
-            // Convert integer part
-            double intValue = 0;
-            for (char c : intPart.toCharArray()) {
-                int digit = Character.digit(c, base);
-                if (digit < 0)
-                    throw new IllegalArgumentException("Invalid digit: " + c);
-                intValue = intValue * base + digit;
-            }
-
-            // Convert fractional part
-            double fracValue = 0;
-            double divisor = base;
-            for (char c : fracPart.toCharArray()) {
-                int digit = Character.digit(c, base);
-                if (digit < 0)
-                    throw new IllegalArgumentException("Invalid digit: " + c);
-                fracValue += (double) digit / divisor;
-                divisor *= base;
-            }
-
-            double result = intValue + fracValue;
-            return isNegative ? -result : result;
-        } else {
-            return Integer.parseInt(numStr, base);
-        }
-    }
-
+  }
 }
-
-
-
-
diff --git a/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java b/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java
index d7f2b6fd685..7c29f75ba0a 100644
--- a/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java
+++ b/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java
@@ -7,8 +7,6 @@
 
 import static org.junit.jupiter.api.Assertions.*;
 
-import java.math.BigDecimal;
-import java.util.Locale;
 import org.apache.calcite.sql.type.ReturnTypes;
 import org.junit.jupiter.api.Test;
 import org.opensearch.sql.calcite.utils.PPLOperandTypes;
@@ -116,55 +114,77 @@ void testToNumberWithZeroIntegerPart() {
 
   @Test
   void testToNumberInvalidBase() {
-    assertThrows(IllegalArgumentException.class, () -> {
-      ToNumberFunction.toNumber("123", 1);
-    });
-    
-    assertThrows(IllegalArgumentException.class, () -> {
-      ToNumberFunction.toNumber("123", 37);
-    });
-    
-    assertThrows(IllegalArgumentException.class, () -> {
-      ToNumberFunction.toNumber("123", 0);
-    });
-    
-    assertThrows(IllegalArgumentException.class, () -> {
-      ToNumberFunction.toNumber("123", -1);
-    });
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> {
+          ToNumberFunction.toNumber("123", 1);
+        });
+
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> {
+          ToNumberFunction.toNumber("123", 37);
+        });
+
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> {
+          ToNumberFunction.toNumber("123", 0);
+        });
+
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> {
+          ToNumberFunction.toNumber("123", -1);
+        });
   }
 
   @Test
   void testToNumberInvalidDigits() {
-    assertThrows(IllegalArgumentException.class, () -> {
-      ToNumberFunction.toNumber("12A", 10);
-    });
-    
-    assertThrows(IllegalArgumentException.class, () -> {
-      ToNumberFunction.toNumber("102", 2);
-    });
-    
-    assertThrows(IllegalArgumentException.class, () -> {
-      ToNumberFunction.toNumber("189", 8);
-    });
-    
-    assertThrows(IllegalArgumentException.class, () -> {
-      ToNumberFunction.toNumber("GHI", 16);
-    });
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> {
+          ToNumberFunction.toNumber("12A", 10);
+        });
+
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> {
+          ToNumberFunction.toNumber("102", 2);
+        });
+
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> {
+          ToNumberFunction.toNumber("189", 8);
+        });
+
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> {
+          ToNumberFunction.toNumber("GHI", 16);
+        });
   }
 
   @Test
   void testToNumberInvalidFractionalDigits() {
-    assertThrows(IllegalArgumentException.class, () -> {
-      ToNumberFunction.toNumber("10.2", 2);
-    });
-    
-    assertThrows(IllegalArgumentException.class, () -> {
-      ToNumberFunction.toNumber("FF.G", 16);
-    });
-    
-    assertThrows(IllegalArgumentException.class, () -> {
-      ToNumberFunction.toNumber("123.ABC", 10);
-    });
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> {
+          ToNumberFunction.toNumber("10.2", 2);
+        });
+
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> {
+          ToNumberFunction.toNumber("FF.G", 16);
+        });
+
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> {
+          ToNumberFunction.toNumber("123.ABC", 10);
+        });
   }
 
   @Test
@@ -177,8 +197,10 @@ void testToNumberEdgeCases() {
 
   @Test
   void testToNumberLargeNumbers() {
-    assertEquals(Integer.MAX_VALUE, ToNumberFunction.toNumber(String.valueOf(Integer.MAX_VALUE), 10));
-    assertEquals(Integer.MIN_VALUE, ToNumberFunction.toNumber(String.valueOf(Integer.MIN_VALUE), 10));
+    assertEquals(
+        Integer.MAX_VALUE, ToNumberFunction.toNumber(String.valueOf(Integer.MAX_VALUE), 10));
+    assertEquals(
+        Integer.MIN_VALUE, ToNumberFunction.toNumber(String.valueOf(Integer.MIN_VALUE), 10));
   }
 
   @Test

From 58d8e1b5714d9f02f80b910da847741cc309f713 Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Tue, 28 Oct 2025 10:53:26 -0700
Subject: [PATCH 24/33] merge conflict fix

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 docs/user/ppl/functions/conversion.rst | 51 ++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/docs/user/ppl/functions/conversion.rst b/docs/user/ppl/functions/conversion.rst
index 849d2334e41..ffe98228c39 100644
--- a/docs/user/ppl/functions/conversion.rst
+++ b/docs/user/ppl/functions/conversion.rst
@@ -117,3 +117,54 @@ Use string in comparison operator example ::
     | True | False | True | False | True | True | null |
     +------+-------+------+-------+------+------+------+
 
+
+
+TONUMBER
+-----------
+
+Description
+>>>>>>>>>>>
+
+The following usage options are available, depending on the parameter types and the number of parameters.
+
+Usage: tonumber(string, [base]) converts the value in first argument to provided base type string in second argument. If second argument is not provided, then it converts to base 10 number representation.
+
+Return type: Number
+
+
+You can use this function with the eval commands and as part of eval expressions.
+Base values can be between 2 and 36.
+
+You can use this function to convert a string representation of a binary number to return the corresponding number in base 10.
+
+Following example converts a string in binary to the number representation::
+
+    os> source=EMP | eval int_value = tonumber('010101',2) | fields int_value | head 1
+    fetched rows / total rows = 1/1
+    +---------------+
+    |  int_value    |
+    |---------------+
+    |  21.0         |
+    +---------------+
+
+
+Following example converts a string in hex to the number representation::
+
+
+    os> source=EMP | eval int_value = tonumber('FA34',16) | fields int_value | head 1
+    fetched rows / total rows = 1/1
+    +---------------+
+    | int_value     |
+    |---------------+
+    | 64052.0       |
+    +---------------+
+
+Following example converts a string in decimal  to the number representation::
+
+     os> source=EMP | eval int_value = tonumber('4598') | fields int_value | head 1
+     fetched rows / total rows = 1/1
+    +---------------+
+    | int_value     |
+    |---------------+
+    | 4598.0        |
+    +---------------+

From 34f86355d4da09a88b761ac3e1190f7a609b1156 Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Sat, 1 Nov 2025 22:48:31 -0700
Subject: [PATCH 25/33] added recommended changes

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 .../function/udf/ToNumberFunction.java        |  24 ++--
 .../function/udf/ToNumberFunctionTest.java    | 105 +++++++-----------
 docs/user/ppl/functions/conversion.rst        |   6 +-
 .../CalcitePPLToNumberFunctionTest.java       |  71 ++++++++++++
 4 files changed, 133 insertions(+), 73 deletions(-)
 create mode 100644 ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLToNumberFunctionTest.java

diff --git a/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java b/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java
index 0c5b576b297..38f1734a8aa 100644
--- a/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java
+++ b/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java
@@ -104,18 +104,26 @@ public static Number toNumber(String numStr, int base) {
 
       // Convert fractional part
       double fracValue = 0;
-      double divisor = base;
-      for (char c : fracPart.toCharArray()) {
-        int digit = Character.digit(c, base);
-        if (digit < 0) throw new IllegalArgumentException("Invalid digit: " + c);
-        fracValue += (double) digit / divisor;
-        divisor *= base;
+      if (base == 10) {
+          double divisor = base;
+          for (char c : fracPart.toCharArray()) {
+              int digit = Character.digit(c, base);
+              if (digit < 0) throw new IllegalArgumentException("Invalid digit: " + c);
+              fracValue += (double) digit / divisor;
+              divisor *= base;
+          }
       }
 
       double result = intValue + fracValue;
-      return isNegative ? -result : result;
+      result =  isNegative ? -result : result;
+      if (base == 10) {
+          return result;
+      }
+      else {
+          return (long) result;
+      }
     } else {
-      return Integer.parseInt(numStr, base);
+      return Long.parseLong(numStr, base);
     }
   }
 }
diff --git a/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java b/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java
index 7c29f75ba0a..3a8c3185240 100644
--- a/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java
+++ b/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java
@@ -27,9 +27,9 @@ void testGetOperandMetadata() {
 
   @Test
   void testToNumberWithDefaultBase() {
-    assertEquals(123, ToNumberFunction.toNumber("123"));
-    assertEquals(0, ToNumberFunction.toNumber("0"));
-    assertEquals(-456, ToNumberFunction.toNumber("-456"));
+    assertEquals(123L, ToNumberFunction.toNumber("123"));
+    assertEquals(0L, ToNumberFunction.toNumber("0"));
+    assertEquals(-456L, ToNumberFunction.toNumber("-456"));
     assertEquals(123.45, ToNumberFunction.toNumber("123.45"));
     assertEquals(-123.45, ToNumberFunction.toNumber("-123.45"));
     assertEquals(0.5, ToNumberFunction.toNumber("0.5"));
@@ -38,78 +38,78 @@ void testToNumberWithDefaultBase() {
 
   @Test
   void testToNumberWithBase10() {
-    assertEquals(123, ToNumberFunction.toNumber("123", 10));
-    assertEquals(0, ToNumberFunction.toNumber("0", 10));
-    assertEquals(-456, ToNumberFunction.toNumber("-456", 10));
+    assertEquals(123L, ToNumberFunction.toNumber("123", 10));
+    assertEquals(0L, ToNumberFunction.toNumber("0", 10));
+    assertEquals(-456L, ToNumberFunction.toNumber("-456", 10));
     assertEquals(123.45, ToNumberFunction.toNumber("123.45", 10));
     assertEquals(-123.45, ToNumberFunction.toNumber("-123.45", 10));
   }
 
   @Test
   void testToNumberWithBase2() {
-    assertEquals(5, ToNumberFunction.toNumber("101", 2));
-    assertEquals(0, ToNumberFunction.toNumber("0", 2));
-    assertEquals(1, ToNumberFunction.toNumber("1", 2));
-    assertEquals(7, ToNumberFunction.toNumber("111", 2));
-    assertEquals(10, ToNumberFunction.toNumber("1010", 2));
+    assertEquals(5L, ToNumberFunction.toNumber("101", 2));
+    assertEquals(0L, ToNumberFunction.toNumber("0", 2));
+    assertEquals(1L, ToNumberFunction.toNumber("1", 2));
+    assertEquals(7L, ToNumberFunction.toNumber("111", 2));
+    assertEquals(10L, ToNumberFunction.toNumber("1010", 2));
   }
 
   @Test
   void testToNumberWithBase8() {
-    assertEquals(64, ToNumberFunction.toNumber("100", 8));
-    assertEquals(8, ToNumberFunction.toNumber("10", 8));
-    assertEquals(83, ToNumberFunction.toNumber("123", 8));
-    assertEquals(511, ToNumberFunction.toNumber("777", 8));
+    assertEquals(64L, ToNumberFunction.toNumber("100", 8));
+    assertEquals(8L, ToNumberFunction.toNumber("10", 8));
+    assertEquals(83L, ToNumberFunction.toNumber("123", 8));
+    assertEquals(511L, ToNumberFunction.toNumber("777", 8));
   }
 
   @Test
   void testToNumberWithBase16() {
-    assertEquals(255, ToNumberFunction.toNumber("FF", 16));
-    assertEquals(16, ToNumberFunction.toNumber("10", 16));
-    assertEquals(171, ToNumberFunction.toNumber("AB", 16));
-    assertEquals(291, ToNumberFunction.toNumber("123", 16));
-    assertEquals(4095, ToNumberFunction.toNumber("FFF", 16));
+    assertEquals(255L, ToNumberFunction.toNumber("FF", 16));
+    assertEquals(16L, ToNumberFunction.toNumber("10", 16));
+    assertEquals(171L, ToNumberFunction.toNumber("AB", 16));
+    assertEquals(291L, ToNumberFunction.toNumber("123", 16));
+    assertEquals(4095L, ToNumberFunction.toNumber("FFF", 16));
   }
 
   @Test
   void testToNumberWithBase36() {
-    assertEquals(35, ToNumberFunction.toNumber("Z", 36));
-    assertEquals(1295, ToNumberFunction.toNumber("ZZ", 36));
-    assertEquals(46655, ToNumberFunction.toNumber("ZZZ", 36));
+    assertEquals(35L, ToNumberFunction.toNumber("Z", 36));
+    assertEquals(1295L, ToNumberFunction.toNumber("ZZ", 36));
+    assertEquals(46655L, ToNumberFunction.toNumber("ZZZ", 36));
   }
 
   @Test
   void testToNumberWithDecimalBase2() {
-    assertEquals(2.5, ToNumberFunction.toNumber("10.1", 2));
-    assertEquals(1.5, ToNumberFunction.toNumber("1.1", 2));
-    assertEquals(3.75, ToNumberFunction.toNumber("11.11", 2));
+    assertEquals(2L, ToNumberFunction.toNumber("10.1", 2));
+    assertEquals(1L, ToNumberFunction.toNumber("1.1", 2));
+    assertEquals(3L, ToNumberFunction.toNumber("11.11", 2));
   }
 
   @Test
   void testToNumberWithDecimalBase16() {
-    assertEquals(255.5, ToNumberFunction.toNumber("FF.8", 16));
-    assertEquals(16.25, ToNumberFunction.toNumber("10.4", 16));
-    assertEquals(171.6875, ToNumberFunction.toNumber("AB.B", 16));
+    assertEquals(255L, ToNumberFunction.toNumber("FF.8", 16));
+    assertEquals(16L, ToNumberFunction.toNumber("10.4", 16));
+    assertEquals(171L, ToNumberFunction.toNumber("AB.B", 16));
   }
 
   @Test
   void testToNumberWithNegativeDecimal() {
-    assertEquals(-2.5, ToNumberFunction.toNumber("-10.1", 2));
-    assertEquals(-255.5, ToNumberFunction.toNumber("-FF.8", 16));
+    assertEquals(-2L, ToNumberFunction.toNumber("-10.1", 2));
+    assertEquals(-255L, ToNumberFunction.toNumber("-FF.8", 16));
     assertEquals(-123.45, ToNumberFunction.toNumber("-123.45", 10));
   }
 
   @Test
   void testToNumberWithEmptyFractionalPart() {
     assertEquals(123.0, ToNumberFunction.toNumber("123.", 10));
-    assertEquals(255.0, ToNumberFunction.toNumber("FF.", 16));
-    assertEquals(5.0, ToNumberFunction.toNumber("101.", 2));
+    assertEquals(255L, ToNumberFunction.toNumber("FF.", 16));
+    assertEquals(5L, ToNumberFunction.toNumber("101.", 2));
   }
 
   @Test
   void testToNumberWithZeroIntegerPart() {
     assertEquals(0.5, ToNumberFunction.toNumber("0.5", 10));
-    assertEquals(0.5, ToNumberFunction.toNumber("0.1", 2));
+    assertEquals(0L, ToNumberFunction.toNumber("0.1", 2));
   }
 
   @Test
@@ -166,31 +166,12 @@ void testToNumberInvalidDigits() {
         });
   }
 
-  @Test
-  void testToNumberInvalidFractionalDigits() {
-    assertThrows(
-        IllegalArgumentException.class,
-        () -> {
-          ToNumberFunction.toNumber("10.2", 2);
-        });
 
-    assertThrows(
-        IllegalArgumentException.class,
-        () -> {
-          ToNumberFunction.toNumber("FF.G", 16);
-        });
-
-    assertThrows(
-        IllegalArgumentException.class,
-        () -> {
-          ToNumberFunction.toNumber("123.ABC", 10);
-        });
-  }
 
   @Test
   void testToNumberEdgeCases() {
-    assertEquals(0, ToNumberFunction.toNumber("0", 2));
-    assertEquals(0, ToNumberFunction.toNumber("0", 36));
+    assertEquals(0L, ToNumberFunction.toNumber("0", 2));
+    assertEquals(0L, ToNumberFunction.toNumber("0", 36));
     assertEquals(0.0, ToNumberFunction.toNumber("0.0", 10));
     assertEquals(0.0, ToNumberFunction.toNumber("0.000", 10));
   }
@@ -198,17 +179,17 @@ void testToNumberEdgeCases() {
   @Test
   void testToNumberLargeNumbers() {
     assertEquals(
-        Integer.MAX_VALUE, ToNumberFunction.toNumber(String.valueOf(Integer.MAX_VALUE), 10));
+            (long) Integer.MAX_VALUE, ToNumberFunction.toNumber(String.valueOf(Integer.MAX_VALUE), 10));
     assertEquals(
-        Integer.MIN_VALUE, ToNumberFunction.toNumber(String.valueOf(Integer.MIN_VALUE), 10));
+            (long) Integer.MIN_VALUE, ToNumberFunction.toNumber(String.valueOf(Integer.MIN_VALUE), 10));
   }
 
   @Test
   void testToNumberCaseInsensitivity() {
-    assertEquals(255, ToNumberFunction.toNumber("ff", 16));
-    assertEquals(255, ToNumberFunction.toNumber("FF", 16));
-    assertEquals(255, ToNumberFunction.toNumber("fF", 16));
-    assertEquals(171, ToNumberFunction.toNumber("ab", 16));
-    assertEquals(171, ToNumberFunction.toNumber("AB", 16));
+    assertEquals(255L, ToNumberFunction.toNumber("ff", 16));
+    assertEquals(255L, ToNumberFunction.toNumber("FF", 16));
+    assertEquals(255L, ToNumberFunction.toNumber("fF", 16));
+    assertEquals(171L, ToNumberFunction.toNumber("ab", 16));
+    assertEquals(171L, ToNumberFunction.toNumber("AB", 16));
   }
 }
diff --git a/docs/user/ppl/functions/conversion.rst b/docs/user/ppl/functions/conversion.rst
index ffe98228c39..0176c6a6003 100644
--- a/docs/user/ppl/functions/conversion.rst
+++ b/docs/user/ppl/functions/conversion.rst
@@ -139,7 +139,7 @@ You can use this function to convert a string representation of a binary number
 
 Following example converts a string in binary to the number representation::
 
-    os> source=EMP | eval int_value = tonumber('010101',2) | fields int_value | head 1
+    os> source=people | eval int_value = tonumber('010101',2) | fields int_value | head 1
     fetched rows / total rows = 1/1
     +---------------+
     |  int_value    |
@@ -151,7 +151,7 @@ Following example converts a string in binary to the number representation::
 Following example converts a string in hex to the number representation::
 
 
-    os> source=EMP | eval int_value = tonumber('FA34',16) | fields int_value | head 1
+    os> source=people | eval int_value = tonumber('FA34',16) | fields int_value | head 1
     fetched rows / total rows = 1/1
     +---------------+
     | int_value     |
@@ -161,7 +161,7 @@ Following example converts a string in hex to the number representation::
 
 Following example converts a string in decimal  to the number representation::
 
-     os> source=EMP | eval int_value = tonumber('4598') | fields int_value | head 1
+     os> source=people | eval int_value = tonumber('4598') | fields int_value | head 1
      fetched rows / total rows = 1/1
     +---------------+
     | int_value     |
diff --git a/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLToNumberFunctionTest.java b/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLToNumberFunctionTest.java
new file mode 100644
index 00000000000..885812a9003
--- /dev/null
+++ b/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLToNumberFunctionTest.java
@@ -0,0 +1,71 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.sql.ppl.calcite;
+
+import org.apache.calcite.rel.RelNode;
+import org.apache.calcite.test.CalciteAssert;
+import org.junit.Test;
+
+public class CalcitePPLToNumberFunctionTest extends CalcitePPLAbstractTest {
+
+  public CalcitePPLToNumberFunctionTest() {
+    super(CalciteAssert.SchemaSpec.SCOTT_WITH_TEMPORAL);
+  }
+
+  @Test
+  public void testNumberBinary() {
+    String ppl = "source=EMP | eval int_value = tonumber('010101',2) | fields int_value|head 1";
+    RelNode root = getRelNode(ppl);
+    String expectedLogical =
+            "LogicalSort(fetch=[1])\n  LogicalProject(int_value=[TONUMBER('010101':VARCHAR, 2)])\n    LogicalTableScan(table=[[scott, EMP]])\n";
+    verifyLogical(root, expectedLogical);
+    String expectedResult = "int_value=21.0\n";
+    verifyResult(root, expectedResult);
+
+    String expectedSparkSql = "SELECT `TONUMBER`('010101', 2) `int_value`\nFROM `scott`.`EMP`\nLIMIT 1";
+    verifyPPLToSparkSQL(root, expectedSparkSql);
+  }
+
+
+    @Test
+    public void testNumberHex() {
+        String ppl = "source=EMP | eval int_value = tonumber('FA34',16) | fields int_value|head 1";
+        RelNode root = getRelNode(ppl);
+        String expectedLogical = "LogicalSort(fetch=[1])\n  LogicalProject(int_value=[TONUMBER('FA34':VARCHAR, 16)])\n    LogicalTableScan(table=[[scott, EMP]])\n";
+        verifyLogical(root, expectedLogical);
+        String expectedResult = "int_value=64052.0\n";
+        verifyResult(root, expectedResult);
+
+        String expectedSparkSql = "SELECT `TONUMBER`('FA34', 16) `int_value`\nFROM `scott`.`EMP`\nLIMIT 1";
+        verifyPPLToSparkSQL(root, expectedSparkSql);
+    }
+
+    @Test
+    public void testNumber() {
+        String ppl = "source=EMP | eval int_value = tonumber('4598') | fields int_value|head 1";
+        RelNode root = getRelNode(ppl);
+        String expectedLogical = "LogicalSort(fetch=[1])\n  LogicalProject(int_value=[TONUMBER('4598':VARCHAR)])\n    LogicalTableScan(table=[[scott, EMP]])\n";
+        verifyLogical(root, expectedLogical);
+        String expectedResult = "int_value=4598.0\n";
+        verifyResult(root, expectedResult);
+
+        String expectedSparkSql = "SELECT `TONUMBER`('4598') `int_value`\nFROM `scott`.`EMP`\nLIMIT 1";
+        verifyPPLToSparkSQL(root, expectedSparkSql);
+    }
+
+    @Test
+    public void testNumberDecimal() {
+        String ppl = "source=EMP | eval int_value = tonumber('4598.54922') | fields int_value|head 1";
+        RelNode root = getRelNode(ppl);
+        String expectedLogical = "LogicalSort(fetch=[1])\n  LogicalProject(int_value=[TONUMBER('4598.54922':VARCHAR)])\n    LogicalTableScan(table=[[scott, EMP]])\n";
+        verifyLogical(root, expectedLogical);
+        String expectedResult = "int_value=4598.54922\n";
+        verifyResult(root, expectedResult);
+
+        String expectedSparkSql = "SELECT `TONUMBER`('4598.54922') `int_value`\nFROM `scott`.`EMP`\nLIMIT 1";
+        verifyPPLToSparkSQL(root, expectedSparkSql);
+    }
+}

From 8279bf3c18889272ee8ac0266a5fdeaa3c4ab5b2 Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Tue, 4 Nov 2025 18:13:10 -0800
Subject: [PATCH 26/33] fixed doctest for conversion.rst and applied spotless

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 .../function/udf/ToNumberFunction.java        | 23 +++--
 .../function/udf/ToNumberFunctionTest.java    |  6 +-
 docs/user/ppl/functions/conversion.rst        | 78 ++++++++---------
 .../CalcitePPLToNumberFunctionTest.java       | 85 +++++++++++--------
 4 files changed, 101 insertions(+), 91 deletions(-)

diff --git a/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java b/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java
index 38f1734a8aa..479cbefaf87 100644
--- a/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java
+++ b/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java
@@ -105,22 +105,21 @@ public static Number toNumber(String numStr, int base) {
       // Convert fractional part
       double fracValue = 0;
       if (base == 10) {
-          double divisor = base;
-          for (char c : fracPart.toCharArray()) {
-              int digit = Character.digit(c, base);
-              if (digit < 0) throw new IllegalArgumentException("Invalid digit: " + c);
-              fracValue += (double) digit / divisor;
-              divisor *= base;
-          }
+        double divisor = base;
+        for (char c : fracPart.toCharArray()) {
+          int digit = Character.digit(c, base);
+          if (digit < 0) throw new IllegalArgumentException("Invalid digit: " + c);
+          fracValue += (double) digit / divisor;
+          divisor *= base;
+        }
       }
 
       double result = intValue + fracValue;
-      result =  isNegative ? -result : result;
+      result = isNegative ? -result : result;
       if (base == 10) {
-          return result;
-      }
-      else {
-          return (long) result;
+        return result;
+      } else {
+        return (long) result;
       }
     } else {
       return Long.parseLong(numStr, base);
diff --git a/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java b/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java
index 3a8c3185240..cd976956408 100644
--- a/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java
+++ b/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java
@@ -166,8 +166,6 @@ void testToNumberInvalidDigits() {
         });
   }
 
-
-
   @Test
   void testToNumberEdgeCases() {
     assertEquals(0L, ToNumberFunction.toNumber("0", 2));
@@ -179,9 +177,9 @@ void testToNumberEdgeCases() {
   @Test
   void testToNumberLargeNumbers() {
     assertEquals(
-            (long) Integer.MAX_VALUE, ToNumberFunction.toNumber(String.valueOf(Integer.MAX_VALUE), 10));
+        (long) Integer.MAX_VALUE, ToNumberFunction.toNumber(String.valueOf(Integer.MAX_VALUE), 10));
     assertEquals(
-            (long) Integer.MIN_VALUE, ToNumberFunction.toNumber(String.valueOf(Integer.MIN_VALUE), 10));
+        (long) Integer.MIN_VALUE, ToNumberFunction.toNumber(String.valueOf(Integer.MIN_VALUE), 10));
   }
 
   @Test
diff --git a/docs/user/ppl/functions/conversion.rst b/docs/user/ppl/functions/conversion.rst
index 0176c6a6003..fd34681b03f 100644
--- a/docs/user/ppl/functions/conversion.rst
+++ b/docs/user/ppl/functions/conversion.rst
@@ -43,21 +43,21 @@ Cast to string example::
 
     os> source=people | eval `cbool` = CAST(true as string), `cint` = CAST(1 as string), `cdate` = CAST(CAST('2012-08-07' as date) as string) | fields `cbool`, `cint`, `cdate`
     fetched rows / total rows = 1/1
-    +-------+------+------------+
-    | cbool | cint | cdate      |
-    |-------+------+------------|
-    | TRUE  | 1    | 2012-08-07 |
-    +-------+------+------------+
+    +---------+--------+------------+
+    | cbool   | cint   | cdate      |
+    |---------+--------+------------|
+    | TRUE    | 1      | 2012-08-07 |
+    +---------+--------+------------+
 
 Cast to number example::
 
     os> source=people | eval `cbool` = CAST(true as int), `cstring` = CAST('1' as int) | fields `cbool`, `cstring`
     fetched rows / total rows = 1/1
-    +-------+---------+
-    | cbool | cstring |
-    |-------+---------|
-    | 1     | 1       |
-    +-------+---------+
+    +---------+-----------+
+    | cbool   | cstring   |
+    |---------+-----------|
+    | 1       | 1         |
+    +---------+-----------+
 
 Cast to date example::
 
@@ -73,11 +73,11 @@ Cast function can be chained::
 
     os> source=people | eval `cbool` = CAST(CAST(true as string) as boolean) | fields `cbool`
     fetched rows / total rows = 1/1
-    +-------+
-    | cbool |
-    |-------|
-    | True  |
-    +-------+
+    +---------+
+    | cbool   |
+    |---------|
+    | True    |
+    +---------+
 
 
 IMPLICIT (AUTO) TYPE CONVERSION
@@ -101,11 +101,11 @@ Use string in arithmetic operator example ::
 
     os> source=people | eval divide="5"/10, multiply="5" * 10, add="5" + 10, minus="5" - 10, concat="5" + "5" | fields divide, multiply, add, minus, concat
     fetched rows / total rows = 1/1
-    +--------+----------+------+-------+--------+
-    | divide | multiply | add  | minus | concat |
-    |--------+----------+------+-------+--------|
-    | 0.5    | 50.0     | 15.0 | -5.0  | 55     |
-    +--------+----------+------+-------+--------+
+    +----------+------------+-------+---------+----------+
+    | divide   | multiply   | add   | minus   | concat   |
+    |----------+------------+-------+---------+----------|
+    | 0.5      | 50.0       | 15.0  | -5.0    | 55       |
+    +----------+------------+-------+---------+----------+
 
 Use string in comparison operator example ::
 
@@ -120,7 +120,7 @@ Use string in comparison operator example ::
 
 
 TONUMBER
------------
+--------
 
 Description
 >>>>>>>>>>>
@@ -141,30 +141,30 @@ Following example converts a string in binary to the number representation::
 
     os> source=people | eval int_value = tonumber('010101',2) | fields int_value | head 1
     fetched rows / total rows = 1/1
-    +---------------+
-    |  int_value    |
-    |---------------+
-    |  21.0         |
-    +---------------+
+    +-------------+
+    | int_value   |
+    |-------------|
+    | 21.0        |
+    +-------------+
 
 
 Following example converts a string in hex to the number representation::
 
-
     os> source=people | eval int_value = tonumber('FA34',16) | fields int_value | head 1
     fetched rows / total rows = 1/1
-    +---------------+
-    | int_value     |
-    |---------------+
-    | 64052.0       |
-    +---------------+
+    +-------------+
+    | int_value   |
+    |-------------|
+    | 64052.0     |
+    +-------------+
 
 Following example converts a string in decimal  to the number representation::
 
-     os> source=people | eval int_value = tonumber('4598') | fields int_value | head 1
-     fetched rows / total rows = 1/1
-    +---------------+
-    | int_value     |
-    |---------------+
-    | 4598.0        |
-    +---------------+
+    os> source=people | eval int_value = tonumber('4598') | fields int_value | head 1
+    fetched rows / total rows = 1/1
+    +-------------+
+    | int_value   |
+    |-------------|
+    | 4598.0      |
+    +-------------+
+
diff --git a/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLToNumberFunctionTest.java b/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLToNumberFunctionTest.java
index 885812a9003..37053e59f51 100644
--- a/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLToNumberFunctionTest.java
+++ b/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLToNumberFunctionTest.java
@@ -20,52 +20,65 @@ public void testNumberBinary() {
     String ppl = "source=EMP | eval int_value = tonumber('010101',2) | fields int_value|head 1";
     RelNode root = getRelNode(ppl);
     String expectedLogical =
-            "LogicalSort(fetch=[1])\n  LogicalProject(int_value=[TONUMBER('010101':VARCHAR, 2)])\n    LogicalTableScan(table=[[scott, EMP]])\n";
+        "LogicalSort(fetch=[1])\n"
+            + "  LogicalProject(int_value=[TONUMBER('010101':VARCHAR, 2)])\n"
+            + "    LogicalTableScan(table=[[scott, EMP]])\n";
     verifyLogical(root, expectedLogical);
     String expectedResult = "int_value=21.0\n";
     verifyResult(root, expectedResult);
 
-    String expectedSparkSql = "SELECT `TONUMBER`('010101', 2) `int_value`\nFROM `scott`.`EMP`\nLIMIT 1";
+    String expectedSparkSql =
+        "SELECT `TONUMBER`('010101', 2) `int_value`\nFROM `scott`.`EMP`\nLIMIT 1";
     verifyPPLToSparkSQL(root, expectedSparkSql);
   }
 
+  @Test
+  public void testNumberHex() {
+    String ppl = "source=EMP | eval int_value = tonumber('FA34',16) | fields int_value|head 1";
+    RelNode root = getRelNode(ppl);
+    String expectedLogical =
+        "LogicalSort(fetch=[1])\n"
+            + "  LogicalProject(int_value=[TONUMBER('FA34':VARCHAR, 16)])\n"
+            + "    LogicalTableScan(table=[[scott, EMP]])\n";
+    verifyLogical(root, expectedLogical);
+    String expectedResult = "int_value=64052.0\n";
+    verifyResult(root, expectedResult);
 
-    @Test
-    public void testNumberHex() {
-        String ppl = "source=EMP | eval int_value = tonumber('FA34',16) | fields int_value|head 1";
-        RelNode root = getRelNode(ppl);
-        String expectedLogical = "LogicalSort(fetch=[1])\n  LogicalProject(int_value=[TONUMBER('FA34':VARCHAR, 16)])\n    LogicalTableScan(table=[[scott, EMP]])\n";
-        verifyLogical(root, expectedLogical);
-        String expectedResult = "int_value=64052.0\n";
-        verifyResult(root, expectedResult);
-
-        String expectedSparkSql = "SELECT `TONUMBER`('FA34', 16) `int_value`\nFROM `scott`.`EMP`\nLIMIT 1";
-        verifyPPLToSparkSQL(root, expectedSparkSql);
-    }
+    String expectedSparkSql =
+        "SELECT `TONUMBER`('FA34', 16) `int_value`\nFROM `scott`.`EMP`\nLIMIT 1";
+    verifyPPLToSparkSQL(root, expectedSparkSql);
+  }
 
-    @Test
-    public void testNumber() {
-        String ppl = "source=EMP | eval int_value = tonumber('4598') | fields int_value|head 1";
-        RelNode root = getRelNode(ppl);
-        String expectedLogical = "LogicalSort(fetch=[1])\n  LogicalProject(int_value=[TONUMBER('4598':VARCHAR)])\n    LogicalTableScan(table=[[scott, EMP]])\n";
-        verifyLogical(root, expectedLogical);
-        String expectedResult = "int_value=4598.0\n";
-        verifyResult(root, expectedResult);
+  @Test
+  public void testNumber() {
+    String ppl = "source=EMP | eval int_value = tonumber('4598') | fields int_value|head 1";
+    RelNode root = getRelNode(ppl);
+    String expectedLogical =
+        "LogicalSort(fetch=[1])\n"
+            + "  LogicalProject(int_value=[TONUMBER('4598':VARCHAR)])\n"
+            + "    LogicalTableScan(table=[[scott, EMP]])\n";
+    verifyLogical(root, expectedLogical);
+    String expectedResult = "int_value=4598.0\n";
+    verifyResult(root, expectedResult);
 
-        String expectedSparkSql = "SELECT `TONUMBER`('4598') `int_value`\nFROM `scott`.`EMP`\nLIMIT 1";
-        verifyPPLToSparkSQL(root, expectedSparkSql);
-    }
+    String expectedSparkSql = "SELECT `TONUMBER`('4598') `int_value`\nFROM `scott`.`EMP`\nLIMIT 1";
+    verifyPPLToSparkSQL(root, expectedSparkSql);
+  }
 
-    @Test
-    public void testNumberDecimal() {
-        String ppl = "source=EMP | eval int_value = tonumber('4598.54922') | fields int_value|head 1";
-        RelNode root = getRelNode(ppl);
-        String expectedLogical = "LogicalSort(fetch=[1])\n  LogicalProject(int_value=[TONUMBER('4598.54922':VARCHAR)])\n    LogicalTableScan(table=[[scott, EMP]])\n";
-        verifyLogical(root, expectedLogical);
-        String expectedResult = "int_value=4598.54922\n";
-        verifyResult(root, expectedResult);
+  @Test
+  public void testNumberDecimal() {
+    String ppl = "source=EMP | eval int_value = tonumber('4598.54922') | fields int_value|head 1";
+    RelNode root = getRelNode(ppl);
+    String expectedLogical =
+        "LogicalSort(fetch=[1])\n"
+            + "  LogicalProject(int_value=[TONUMBER('4598.54922':VARCHAR)])\n"
+            + "    LogicalTableScan(table=[[scott, EMP]])\n";
+    verifyLogical(root, expectedLogical);
+    String expectedResult = "int_value=4598.54922\n";
+    verifyResult(root, expectedResult);
 
-        String expectedSparkSql = "SELECT `TONUMBER`('4598.54922') `int_value`\nFROM `scott`.`EMP`\nLIMIT 1";
-        verifyPPLToSparkSQL(root, expectedSparkSql);
-    }
+    String expectedSparkSql =
+        "SELECT `TONUMBER`('4598.54922') `int_value`\nFROM `scott`.`EMP`\nLIMIT 1";
+    verifyPPLToSparkSQL(root, expectedSparkSql);
+  }
 }

From b5346a6dcfb385f040cc103f8ad480678dc0156a Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Tue, 4 Nov 2025 18:20:04 -0800
Subject: [PATCH 27/33] removed decimal point from hex

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 .../function/udf/ToNumberFunctionTest.java    | 22 +++++++++----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java b/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java
index cd976956408..d457a8a36a9 100644
--- a/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java
+++ b/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java
@@ -80,36 +80,36 @@ void testToNumberWithBase36() {
 
   @Test
   void testToNumberWithDecimalBase2() {
-    assertEquals(2L, ToNumberFunction.toNumber("10.1", 2));
-    assertEquals(1L, ToNumberFunction.toNumber("1.1", 2));
-    assertEquals(3L, ToNumberFunction.toNumber("11.11", 2));
+    assertEquals(2L, ToNumberFunction.toNumber("10", 2));
+    assertEquals(1L, ToNumberFunction.toNumber("1", 2));
+    assertEquals(3L, ToNumberFunction.toNumber("11", 2));
   }
 
   @Test
   void testToNumberWithDecimalBase16() {
-    assertEquals(255L, ToNumberFunction.toNumber("FF.8", 16));
-    assertEquals(16L, ToNumberFunction.toNumber("10.4", 16));
-    assertEquals(171L, ToNumberFunction.toNumber("AB.B", 16));
+    assertEquals(255L, ToNumberFunction.toNumber("FF", 16));
+    assertEquals(16L, ToNumberFunction.toNumber("10", 16));
+    assertEquals(171L, ToNumberFunction.toNumber("AB", 16));
   }
 
   @Test
   void testToNumberWithNegativeDecimal() {
-    assertEquals(-2L, ToNumberFunction.toNumber("-10.1", 2));
-    assertEquals(-255L, ToNumberFunction.toNumber("-FF.8", 16));
+    assertEquals(-2L, ToNumberFunction.toNumber("-10", 2));
+    assertEquals(-255L, ToNumberFunction.toNumber("-FF", 16));
     assertEquals(-123.45, ToNumberFunction.toNumber("-123.45", 10));
   }
 
   @Test
   void testToNumberWithEmptyFractionalPart() {
     assertEquals(123.0, ToNumberFunction.toNumber("123.", 10));
-    assertEquals(255L, ToNumberFunction.toNumber("FF.", 16));
-    assertEquals(5L, ToNumberFunction.toNumber("101.", 2));
+    assertEquals(255L, ToNumberFunction.toNumber("FF", 16));
+    assertEquals(5L, ToNumberFunction.toNumber("101", 2));
   }
 
   @Test
   void testToNumberWithZeroIntegerPart() {
     assertEquals(0.5, ToNumberFunction.toNumber("0.5", 10));
-    assertEquals(0L, ToNumberFunction.toNumber("0.1", 2));
+    assertEquals(0L, ToNumberFunction.toNumber("0", 2));
   }
 
   @Test

From 7cf867b4fa7a1e170df483c3b84e992b62c771a0 Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Wed, 5 Nov 2025 09:56:12 -0800
Subject: [PATCH 28/33] added doctest fixes

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 docs/user/ppl/functions/conversion.rst | 70 +++++++++++++-------------
 1 file changed, 35 insertions(+), 35 deletions(-)

diff --git a/docs/user/ppl/functions/conversion.rst b/docs/user/ppl/functions/conversion.rst
index fd34681b03f..52eb04b8e63 100644
--- a/docs/user/ppl/functions/conversion.rst
+++ b/docs/user/ppl/functions/conversion.rst
@@ -43,21 +43,21 @@ Cast to string example::
 
     os> source=people | eval `cbool` = CAST(true as string), `cint` = CAST(1 as string), `cdate` = CAST(CAST('2012-08-07' as date) as string) | fields `cbool`, `cint`, `cdate`
     fetched rows / total rows = 1/1
-    +---------+--------+------------+
-    | cbool   | cint   | cdate      |
-    |---------+--------+------------|
-    | TRUE    | 1      | 2012-08-07 |
-    +---------+--------+------------+
+    +-------+------+------------+
+    | cbool | cint | cdate      |
+    |-------+------+------------|
+    | TRUE  | 1    | 2012-08-07 |
+    +-------+------+------------+
 
 Cast to number example::
 
     os> source=people | eval `cbool` = CAST(true as int), `cstring` = CAST('1' as int) | fields `cbool`, `cstring`
     fetched rows / total rows = 1/1
-    +---------+-----------+
-    | cbool   | cstring   |
-    |---------+-----------|
-    | 1       | 1         |
-    +---------+-----------+
+    +-------+---------+
+    | cbool | cstring |
+    |-------+---------|
+    | 1     | 1       |
+    +-------+---------+
 
 Cast to date example::
 
@@ -73,11 +73,11 @@ Cast function can be chained::
 
     os> source=people | eval `cbool` = CAST(CAST(true as string) as boolean) | fields `cbool`
     fetched rows / total rows = 1/1
-    +---------+
-    | cbool   |
-    |---------|
-    | True    |
-    +---------+
+    +-------+
+    | cbool |
+    |-------|
+    | True  |
+    +-------+
 
 
 IMPLICIT (AUTO) TYPE CONVERSION
@@ -101,11 +101,11 @@ Use string in arithmetic operator example ::
 
     os> source=people | eval divide="5"/10, multiply="5" * 10, add="5" + 10, minus="5" - 10, concat="5" + "5" | fields divide, multiply, add, minus, concat
     fetched rows / total rows = 1/1
-    +----------+------------+-------+---------+----------+
-    | divide   | multiply   | add   | minus   | concat   |
-    |----------+------------+-------+---------+----------|
-    | 0.5      | 50.0       | 15.0  | -5.0    | 55       |
-    +----------+------------+-------+---------+----------+
+    +--------+----------+------+-------+--------+
+    | divide | multiply | add  | minus | concat |
+    |--------+----------+------+-------+--------|
+    | 0.5    | 50.0     | 15.0 | -5.0  | 55     |
+    +--------+----------+------+-------+--------+
 
 Use string in comparison operator example ::
 
@@ -141,30 +141,30 @@ Following example converts a string in binary to the number representation::
 
     os> source=people | eval int_value = tonumber('010101',2) | fields int_value | head 1
     fetched rows / total rows = 1/1
-    +-------------+
-    | int_value   |
-    |-------------|
-    | 21.0        |
-    +-------------+
+    +-----------+
+    | int_value |
+    |-----------|
+    | 21.0      |
+    +-----------+
 
 
 Following example converts a string in hex to the number representation::
 
     os> source=people | eval int_value = tonumber('FA34',16) | fields int_value | head 1
     fetched rows / total rows = 1/1
-    +-------------+
-    | int_value   |
-    |-------------|
-    | 64052.0     |
-    +-------------+
+    +-----------+
+    | int_value |
+    |-----------|
+    | 64052.0   |
+    +-----------+
 
 Following example converts a string in decimal  to the number representation::
 
     os> source=people | eval int_value = tonumber('4598') | fields int_value | head 1
     fetched rows / total rows = 1/1
-    +-------------+
-    | int_value   |
-    |-------------|
-    | 4598.0      |
-    +-------------+
+    +-----------+
+    | int_value |
+    |-----------|
+    | 4598.0    |
+    +-----------+
 

From 46f010bb62eca84723683347d56cf31323f9ff5b Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Wed, 5 Nov 2025 23:11:47 -0800
Subject: [PATCH 29/33] removed unused variables

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 .../sql/expression/function/udf/ToNumberFunction.java    | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java b/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java
index 479cbefaf87..ba30a7a7d1d 100644
--- a/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java
+++ b/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java
@@ -36,14 +36,7 @@ public ToNumberFunction() {
         NullPolicy.ANY);
   }
 
-  public static final String DURATION_FORMAT = "duration";
-  public static final String DURATION_MILLIS_FORMAT = "duration_millis";
-  public static final String HEX_FORMAT = "hex";
-  public static final String COMMAS_FORMAT = "commas";
-  public static final String BINARY_FORMAT = "binary";
-  public static final SqlFunctions.DateFormatFunction dateTimeFormatter =
-      new SqlFunctions.DateFormatFunction();
-  public static final String format24hour = "%H:%M:%S"; // 24-hour format
+
 
   @Override
   public SqlReturnTypeInference getReturnTypeInference() {

From b7afa1713253d1adc49d343467cdda50d98869a4 Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Thu, 6 Nov 2025 06:36:34 -0800
Subject: [PATCH 30/33] spotless

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 .../sql/expression/function/udf/ToNumberFunction.java          | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java b/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java
index ba30a7a7d1d..5b3a49fe549 100644
--- a/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java
+++ b/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java
@@ -13,7 +13,6 @@
 import org.apache.calcite.linq4j.tree.Expression;
 import org.apache.calcite.linq4j.tree.Expressions;
 import org.apache.calcite.rex.RexCall;
-import org.apache.calcite.runtime.SqlFunctions;
 import org.apache.calcite.sql.type.ReturnTypes;
 import org.apache.calcite.sql.type.SqlReturnTypeInference;
 import org.opensearch.sql.calcite.utils.PPLOperandTypes;
@@ -36,8 +35,6 @@ public ToNumberFunction() {
         NullPolicy.ANY);
   }
 
-
-
   @Override
   public SqlReturnTypeInference getReturnTypeInference() {
     return ReturnTypes.DOUBLE_FORCE_NULLABLE;

From 0f0125a127778b29f74f69aeb16119d9d3716074 Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Thu, 6 Nov 2025 10:24:54 -0800
Subject: [PATCH 31/33] made recommended changes to simply parse to number,
 null when malformed

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 .../function/udf/ToNumberFunction.java        | 52 +++++--------------
 .../function/udf/ToNumberFunctionTest.java    | 29 +++--------
 2 files changed, 19 insertions(+), 62 deletions(-)

diff --git a/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java b/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java
index 5b3a49fe549..2557121b0c8 100644
--- a/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java
+++ b/core/src/main/java/org/opensearch/sql/expression/function/udf/ToNumberFunction.java
@@ -5,6 +5,7 @@
 
 package org.opensearch.sql.expression.function.udf;
 
+import java.math.BigInteger;
 import java.util.List;
 import org.apache.calcite.adapter.enumerable.NotNullImplementor;
 import org.apache.calcite.adapter.enumerable.NullPolicy;
@@ -69,50 +70,23 @@ public static Number toNumber(String numStr) {
   @Strict
   public static Number toNumber(String numStr, int base) {
     if (base < 2 || base > 36) {
-      throw new IllegalArgumentException("Base must be between 2 and 36");
+      throw new IllegalArgumentException("Base has to be between 2 and 36.");
     }
-
-    if (numStr.contains(".")) {
-
-      boolean isNegative = numStr.startsWith("-");
-      if (isNegative) {
-        numStr = numStr.substring(1);
-      }
-
-      // Split integer and fractional parts
-      String[] parts = numStr.split("\\.");
-      String intPart = parts[0];
-      String fracPart = parts.length > 1 ? parts[1] : "";
-
-      // Convert integer part
-      double intValue = 0;
-      for (char c : intPart.toCharArray()) {
-        int digit = Character.digit(c, base);
-        if (digit < 0) throw new IllegalArgumentException("Invalid digit: " + c);
-        intValue = intValue * base + digit;
-      }
-
-      // Convert fractional part
-      double fracValue = 0;
+    Number result = null;
+    try {
       if (base == 10) {
-        double divisor = base;
-        for (char c : fracPart.toCharArray()) {
-          int digit = Character.digit(c, base);
-          if (digit < 0) throw new IllegalArgumentException("Invalid digit: " + c);
-          fracValue += (double) digit / divisor;
-          divisor *= base;
+        if (numStr.contains(".")) {
+          result = Double.parseDouble(numStr);
+        } else {
+          result = Long.parseLong(numStr);
         }
-      }
-
-      double result = intValue + fracValue;
-      result = isNegative ? -result : result;
-      if (base == 10) {
-        return result;
       } else {
-        return (long) result;
+        BigInteger bigInteger = new BigInteger(numStr, base);
+        result = bigInteger.longValue();
       }
-    } else {
-      return Long.parseLong(numStr, base);
+    } catch (Exception e) {
+
     }
+    return result;
   }
 }
diff --git a/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java b/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java
index d457a8a36a9..34ed102ec5b 100644
--- a/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java
+++ b/core/src/test/java/org/opensearch/sql/expression/function/udf/ToNumberFunctionTest.java
@@ -141,29 +141,12 @@ void testToNumberInvalidBase() {
 
   @Test
   void testToNumberInvalidDigits() {
-    assertThrows(
-        IllegalArgumentException.class,
-        () -> {
-          ToNumberFunction.toNumber("12A", 10);
-        });
-
-    assertThrows(
-        IllegalArgumentException.class,
-        () -> {
-          ToNumberFunction.toNumber("102", 2);
-        });
-
-    assertThrows(
-        IllegalArgumentException.class,
-        () -> {
-          ToNumberFunction.toNumber("189", 8);
-        });
-
-    assertThrows(
-        IllegalArgumentException.class,
-        () -> {
-          ToNumberFunction.toNumber("GHI", 16);
-        });
+    assertEquals(null, ToNumberFunction.toNumber("12A", 10));
+    assertEquals(null, ToNumberFunction.toNumber("102", 2));
+    assertEquals(null, ToNumberFunction.toNumber("101.101", 2));
+    assertEquals(null, ToNumberFunction.toNumber("189", 8));
+    assertEquals(null, ToNumberFunction.toNumber("GHI", 16));
+    assertEquals(null, ToNumberFunction.toNumber("FF.8", 16));
   }
 
   @Test

From 804db79a7ad546937cece7a99eea0e84af32c66a Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Sat, 8 Nov 2025 16:51:14 -0800
Subject: [PATCH 32/33] hex max limit doc and unit tests

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 docs/user/ppl/functions/conversion.rst        |  3 +-
 .../CalcitePPLToNumberFunctionTest.java       | 80 +++++++++++++++++++
 2 files changed, 82 insertions(+), 1 deletion(-)

diff --git a/docs/user/ppl/functions/conversion.rst b/docs/user/ppl/functions/conversion.rst
index ca9297b1f0d..c55e868f2cd 100644
--- a/docs/user/ppl/functions/conversion.rst
+++ b/docs/user/ppl/functions/conversion.rst
@@ -133,7 +133,8 @@ Return type: Number
 
 
 You can use this function with the eval commands and as part of eval expressions.
-Base values can be between 2 and 36.
+Base values can be between 2 and 36. The maximum value supported for base 10 is +(2-2^-52)·2^1023 and minimum is -(2-2^-52)·2^1023.
+The maximum for other supported bases is 2^63-1 (or 7FFFFFFFFFFFFFFF)   and minimum is -2^63 (or -7FFFFFFFFFFFFFFF).
 
 You can use this function to convert a string representation of a binary number to return the corresponding number in base 10.
 
diff --git a/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLToNumberFunctionTest.java b/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLToNumberFunctionTest.java
index 37053e59f51..448cddeefec 100644
--- a/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLToNumberFunctionTest.java
+++ b/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLToNumberFunctionTest.java
@@ -49,6 +49,86 @@ public void testNumberHex() {
     verifyPPLToSparkSQL(root, expectedSparkSql);
   }
 
+
+    @Test
+    public void testNumberHexMinLimit() {
+        String ppl =
+                "source=EMP | eval long_value = tonumber('-7FFFFFFFFFFFFFFF',16) | fields long_value|head"
+                        + " 1";
+        RelNode root = getRelNode(ppl);
+        String expectedLogical =
+                "LogicalSort(fetch=[1])\n"
+                        + "  LogicalProject(long_value=[TONUMBER('-7FFFFFFFFFFFFFFF':VARCHAR, 16)])\n"
+                        + "    LogicalTableScan(table=[[scott, EMP]])\n";
+        verifyLogical(root, expectedLogical);
+        String expectedResult = "long_value=-9.223372036854776E18\n";
+        verifyResult(root, expectedResult);
+
+        String expectedSparkSql =
+                "SELECT `TONUMBER`('-7FFFFFFFFFFFFFFF', 16) `long_value`\nFROM `scott`.`EMP`\nLIMIT 1";
+
+        verifyPPLToSparkSQL(root, expectedSparkSql);
+    }
+
+  @Test
+  public void testNumberHexMaxLimit() {
+    String ppl =
+        "source=EMP | eval long_value = tonumber('7FFFFFFFFFFFFFFF',16) | fields long_value|head"
+            + " 1";
+    RelNode root = getRelNode(ppl);
+    String expectedLogical =
+        "LogicalSort(fetch=[1])\n"
+            + "  LogicalProject(long_value=[TONUMBER('7FFFFFFFFFFFFFFF':VARCHAR, 16)])\n"
+            + "    LogicalTableScan(table=[[scott, EMP]])\n";
+    verifyLogical(root, expectedLogical);
+    String expectedResult = "long_value=9.223372036854776E18\n";
+    verifyResult(root, expectedResult);
+
+    String expectedSparkSql =
+        "SELECT `TONUMBER`('7FFFFFFFFFFFFFFF', 16) `long_value`\nFROM `scott`.`EMP`\nLIMIT 1";
+
+    verifyPPLToSparkSQL(root, expectedSparkSql);
+  }
+
+  @Test
+  public void testNumberHexOverNegativeMaxLimit() {
+    String ppl =
+        "source=EMP | eval long_value = tonumber('-FFFFFFFFFFFFFFFF',16) | fields long_value|head"
+            + " 1";
+    RelNode root = getRelNode(ppl);
+    String expectedLogical =
+        "LogicalSort(fetch=[1])\n"
+            + "  LogicalProject(long_value=[TONUMBER('-FFFFFFFFFFFFFFFF':VARCHAR, 16)])\n"
+            + "    LogicalTableScan(table=[[scott, EMP]])\n";
+    verifyLogical(root, expectedLogical);
+    String expectedResult = "long_value=1.0\n";
+    verifyResult(root, expectedResult);
+
+    String expectedSparkSql =
+        "SELECT `TONUMBER`('-FFFFFFFFFFFFFFFF', 16) `long_value`\nFROM `scott`.`EMP`\nLIMIT 1";
+
+    verifyPPLToSparkSQL(root, expectedSparkSql);
+  }
+
+  @Test
+  public void testNumberHexOverPositiveMaxLimit() {
+    String ppl =
+        "source=EMP | eval long_value = tonumber('FFFFFFFFFFFFFFFF',16) | fields long_value|head 1";
+    RelNode root = getRelNode(ppl);
+    String expectedLogical =
+        "LogicalSort(fetch=[1])\n"
+            + "  LogicalProject(long_value=[TONUMBER('FFFFFFFFFFFFFFFF':VARCHAR, 16)])\n"
+            + "    LogicalTableScan(table=[[scott, EMP]])\n";
+    verifyLogical(root, expectedLogical);
+    String expectedResult = "long_value=-1.0\n";
+    verifyResult(root, expectedResult);
+
+    String expectedSparkSql =
+        "SELECT `TONUMBER`('FFFFFFFFFFFFFFFF', 16) `long_value`\nFROM `scott`.`EMP`\nLIMIT 1";
+
+    verifyPPLToSparkSQL(root, expectedSparkSql);
+  }
+
   @Test
   public void testNumber() {
     String ppl = "source=EMP | eval int_value = tonumber('4598') | fields int_value|head 1";

From 75883979380e8cad8b0f4e2318ecaf748fd6d0aa Mon Sep 17 00:00:00 2001
From: Asif Bashar <asif.bashar@gmail.com>
Date: Sun, 9 Nov 2025 10:51:54 -0800
Subject: [PATCH 33/33] fix to spotless

Signed-off-by: Asif Bashar <asif.bashar@gmail.com>
---
 .../CalcitePPLToNumberFunctionTest.java       | 37 +++++++++----------
 1 file changed, 18 insertions(+), 19 deletions(-)

diff --git a/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLToNumberFunctionTest.java b/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLToNumberFunctionTest.java
index 448cddeefec..bd4f2c293b6 100644
--- a/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLToNumberFunctionTest.java
+++ b/ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLToNumberFunctionTest.java
@@ -49,26 +49,25 @@ public void testNumberHex() {
     verifyPPLToSparkSQL(root, expectedSparkSql);
   }
 
+  @Test
+  public void testNumberHexMinLimit() {
+    String ppl =
+        "source=EMP | eval long_value = tonumber('-7FFFFFFFFFFFFFFF',16) | fields long_value|head"
+            + " 1";
+    RelNode root = getRelNode(ppl);
+    String expectedLogical =
+        "LogicalSort(fetch=[1])\n"
+            + "  LogicalProject(long_value=[TONUMBER('-7FFFFFFFFFFFFFFF':VARCHAR, 16)])\n"
+            + "    LogicalTableScan(table=[[scott, EMP]])\n";
+    verifyLogical(root, expectedLogical);
+    String expectedResult = "long_value=-9.223372036854776E18\n";
+    verifyResult(root, expectedResult);
+
+    String expectedSparkSql =
+        "SELECT `TONUMBER`('-7FFFFFFFFFFFFFFF', 16) `long_value`\nFROM `scott`.`EMP`\nLIMIT 1";
 
-    @Test
-    public void testNumberHexMinLimit() {
-        String ppl =
-                "source=EMP | eval long_value = tonumber('-7FFFFFFFFFFFFFFF',16) | fields long_value|head"
-                        + " 1";
-        RelNode root = getRelNode(ppl);
-        String expectedLogical =
-                "LogicalSort(fetch=[1])\n"
-                        + "  LogicalProject(long_value=[TONUMBER('-7FFFFFFFFFFFFFFF':VARCHAR, 16)])\n"
-                        + "    LogicalTableScan(table=[[scott, EMP]])\n";
-        verifyLogical(root, expectedLogical);
-        String expectedResult = "long_value=-9.223372036854776E18\n";
-        verifyResult(root, expectedResult);
-
-        String expectedSparkSql =
-                "SELECT `TONUMBER`('-7FFFFFFFFFFFFFFF', 16) `long_value`\nFROM `scott`.`EMP`\nLIMIT 1";
-
-        verifyPPLToSparkSQL(root, expectedSparkSql);
-    }
+    verifyPPLToSparkSQL(root, expectedSparkSql);
+  }
 
   @Test
   public void testNumberHexMaxLimit() {