Implicit casting

Author: carlosdelest

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/analysis/Analyzer.java

@@ -65,6 +65,7 @@
 import org.elasticsearch.xpack.esql.expression.function.scalar.convert.ToLong;
 import org.elasticsearch.xpack.esql.expression.function.scalar.convert.ToUnsignedLong;
 import org.elasticsearch.xpack.esql.expression.function.scalar.nulls.Coalesce;
+import org.elasticsearch.xpack.esql.expression.function.vector.VectorFunction;
 import org.elasticsearch.xpack.esql.expression.predicate.operator.arithmetic.DateTimeArithmeticOperation;
 import org.elasticsearch.xpack.esql.expression.predicate.operator.arithmetic.EsqlArithmeticOperation;
 import org.elasticsearch.xpack.esql.expression.predicate.operator.comparison.In;
@@ -1365,9 +1366,11 @@ private static Expression cast(org.elasticsearch.xpack.esql.core.expression.func
             if (f instanceof EsqlArithmeticOperation || f instanceof BinaryComparison) {
                 return processBinaryOperator((BinaryOperator) f);
             }
+            if (f instanceof VectorFunction vectorFunction) {
+                return processVectorFunction(f);
+            }
             return f;
         }
-
         private static Expression processScalarOrGroupingFunction(
             org.elasticsearch.xpack.esql.core.expression.function.Function f,
             EsqlFunctionRegistry registry
@@ -1564,6 +1567,25 @@ private static Expression castStringLiteral(Expression from, DataType target) {
                 return unresolvedAttribute(from, target.toString(), e);
             }
         }
+
+        private static Expression processVectorFunction(org.elasticsearch.xpack.esql.core.expression.function.Function vectorFunction) {
+            List<Expression> args = vectorFunction.arguments();
+            List<Expression> newArgs = new ArrayList<>();
+            for (Expression arg : args) {
+                if (arg.resolved() && arg.dataType().isNumeric() && arg.foldable()) {
+                    Object folded = arg.fold(FoldContext.small() /* TODO remove me */);
+                    if (folded instanceof List) {
+                        Literal denseVector = new Literal(arg.source(), folded, DataType.DENSE_VECTOR);
+                        newArgs.add(denseVector);
+                        continue;
+                    }
+                }
+                newArgs.add(arg);
+            }
+
+            return vectorFunction.replaceChildren(newArgs);
+        }
+
     }
 
     /**

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/vector/Knn.java

@@ -52,7 +52,7 @@
 import static org.elasticsearch.xpack.esql.core.type.DataType.INTEGER;
 import static org.elasticsearch.xpack.esql.expression.function.fulltext.Match.getNameFromFieldAttribute;
 
-public class Knn extends FullTextFunction implements OptionalArgument {
+public class Knn extends FullTextFunction implements OptionalArgument, VectorFunction {
 
     public static final NamedWriteableRegistry.Entry ENTRY = new NamedWriteableRegistry.Entry(Expression.class, "Knn", Knn::readFrom);
 
@@ -110,7 +110,7 @@ protected TypeResolution resolveParams() {
         }
 
         return isNotNull(field(), sourceText(), FIRST).and(isType(field(), dt -> dt == DENSE_VECTOR, sourceText(), FIRST, "dense_vector"))
-            .and(TypeResolutions.isNumeric(query(), sourceText(), TypeResolutions.ParamOrdinal.SECOND));
+            .and(isType(query(), dt -> dt == DENSE_VECTOR, sourceText(), TypeResolutions.ParamOrdinal.SECOND));
     }
 
     @Override

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/vector/VectorFunction.java

@@ -0,0 +1,16 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+package org.elasticsearch.xpack.esql.expression.function.vector;
+
+/**
+ * Marker interface for vector functions. Makes possible to do implicit casting
+ * from multi values to dense_vector field types, so parameters are actually
+ * processed as dense_vectors in vector functions
+ */
+public interface VectorFunction {
+}

x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/analysis/AnalyzerTests.java

@@ -49,6 +49,7 @@
 import org.elasticsearch.xpack.esql.expression.function.fulltext.QueryString;
 import org.elasticsearch.xpack.esql.expression.function.scalar.string.Concat;
 import org.elasticsearch.xpack.esql.expression.function.scalar.string.Substring;
+import org.elasticsearch.xpack.esql.expression.function.vector.Knn;
 import org.elasticsearch.xpack.esql.expression.predicate.operator.comparison.Equals;
 import org.elasticsearch.xpack.esql.expression.predicate.operator.comparison.GreaterThan;
 import org.elasticsearch.xpack.esql.index.EsIndex;
@@ -2347,6 +2348,24 @@ public void testImplicitCasting() {
         assertThat(e.getMessage(), containsString("[+] has arguments with incompatible types [datetime] and [datetime]"));
     }
 
+    public void testDenseVectorImplicitCasting() {
+        Analyzer analyzer = analyzer(loadMapping("mapping-dense_vector.json", "vectors"));
+
+        var plan = analyze("""
+            from test | where knn(vector, [0.342, 0.164, 0.234])
+            """,
+            "mapping-dense_vector.json");
+
+        var limit = as(plan, Limit.class);
+        var filter = as(limit.child(), Filter.class);
+        var knn = as(filter.condition(), Knn.class);
+        var field = knn.field();
+        var queryVector = as(knn.query(), Literal.class);
+        assertEquals(DataType.DENSE_VECTOR, queryVector.dataType());
+        assertThat(queryVector.value(), equalTo(List.of(0.342, 0.164, 0.234)));
+    }
+
+
     public void testRateRequiresCounterTypes() {
         assumeTrue("rate requires snapshot builds", Build.current().isSnapshot());
         Analyzer analyzer = analyzer(tsdbIndexResolution());