ESQL: TO_LOWER process all values (#124676)

docs/changelog/124676.yaml

@@ -0,0 +1,6 @@
+pr: 124676
+summary: TO_LOWER processes all values
+area: ES|QL
+type: bug
+issues:
+ - 124002

x-pack/plugin/esql/qa/testFixtures/src/main/resources/string.csv-spec

@@ -1399,6 +1399,20 @@ emp_no:integer  | first_name:keyword    | name_lower:keyword
 ;
 
 
+toLowerMv
+required_capability: to_lower_mv
+// tag::to_lower_mv[]
+ROW v = TO_LOWER(["Some", "Text"])
+// end::to_lower_mv[]
+;
+
+// tag::to_lower_mv-result[]
+   v:keyword
+["some", "text"]
+// end::to_lower_mv-result[]
+;
+
+
 toUpperRow#[skip:-8.12.99]
 // tag::to_upper[]
 ROW message = "Some Text"
@@ -1421,6 +1435,20 @@ emp_no:integer  | first_name:keyword    | name_upper:keyword
 ;
 
 
+toUpperMv
+required_capability: to_lower_mv
+// tag::to_upper_mv[]
+ROW v = TO_UPPER(["Some", "Text"])
+// end::to_upper_mv[]
+;
+
+// tag::to_upper_mv-result[]
+   v:keyword
+["SOME", "TEXT"]
+// end::to_upper_mv-result[]
+;
+
+
 toUpperLowerUnicode#[skip:-8.12.99]
 row a = "π/2 + a + B + Λ ºC" | eval lower = to_lower(a), upper = to_upper(a) | keep a, upper, lower;
 

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/action/EsqlCapabilities.java

@@ -840,6 +840,11 @@ public enum Cap {
          */
         FIX_JOIN_MASKING_EVAL,
 
+        /**
+         * Do {@code TO_LOWER} and {@code TO_UPPER} process all field values?
+         */
+        TO_LOWER_MV,
+
         /**
          * Resolve groupings before resolving references to groupings in the aggregations.
          */

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/scalar/convert/ToStringFromAggregateMetricDoubleEvaluator.java

@@ -14,6 +14,7 @@
 import org.elasticsearch.compute.data.Vector;
 import org.elasticsearch.compute.operator.DriverContext;
 import org.elasticsearch.compute.operator.EvalOperator;
+import org.elasticsearch.core.Releasables;
 import org.elasticsearch.xpack.esql.core.tree.Source;
 
 import static org.elasticsearch.xpack.esql.type.EsqlDataTypeConverter.aggregateMetricDoubleBlockToString;
@@ -63,7 +64,7 @@ public Block evalBlock(Block b) {
 
     @Override
     public void close() {
-        field.close();
+        Releasables.closeExpectNoException(field);
     }
 
     public static class Factory implements EvalOperator.ExpressionEvaluator.Factory {

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/scalar/string/ChangeCase.java

@@ -9,7 +9,7 @@
 
 import org.apache.lucene.util.BytesRef;
 import org.elasticsearch.common.lucene.BytesRefs;
-import org.elasticsearch.compute.ann.Evaluator;
+import org.elasticsearch.compute.ann.ConvertEvaluator;
 import org.elasticsearch.compute.ann.Fixed;
 import org.elasticsearch.compute.operator.EvalOperator;
 import org.elasticsearch.xpack.esql.core.expression.Expression;
@@ -99,7 +99,7 @@ public Expression replaceChildren(List<Expression> newChildren) {
         return replaceChild(newChildren.get(0));
     }
 
-    @Evaluator
+    @ConvertEvaluator
     static BytesRef process(BytesRef val, @Fixed Locale locale, @Fixed Case caseType) {
         return BytesRefs.toBytesRef(caseType.process(val.utf8ToString(), locale));
     }

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/scalar/string/ToLower.java

@@ -27,17 +27,11 @@ public class ToLower extends ChangeCase {
     @FunctionInfo(
         returnType = { "keyword" },
         description = "Returns a new string representing the input string converted to lower case.",
-        examples = @Example(file = "string", tag = "to_lower")
+        examples = { @Example(file = "string", tag = "to_lower"), @Example(file = "string", tag = "to_lower_mv"), }
     )
-    public ToLower(
-        Source source,
-        @Param(
-            name = "str",
-            type = { "keyword", "text" },
-            description = "String expression. If `null`, the function returns `null`."
-        ) Expression field,
-        Configuration configuration
-    ) {
+    public ToLower(Source source, @Param(name = "str", type = { "keyword", "text" }, description = """
+        String expression. If `null`, the function returns `null`.
+        The input can be a single- or multi-valued column or an expression.""") Expression field, Configuration configuration) {
         super(source, field, configuration, Case.LOWER);
     }
 

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/scalar/string/ToUpper.java

@@ -29,15 +29,9 @@ public class ToUpper extends ChangeCase {
         description = "Returns a new string representing the input string converted to upper case.",
         examples = @Example(file = "string", tag = "to_upper")
     )
-    public ToUpper(
-        Source source,
-        @Param(
-            name = "str",
-            type = { "keyword", "text" },
-            description = "String expression. If `null`, the function returns `null`."
-        ) Expression field,
-        Configuration configuration
-    ) {
+    public ToUpper(Source source, @Param(name = "str", type = { "keyword", "text" }, description = """
+        String expression. If `null`, the function returns `null`.
+        The input can be a single- or multi-valued column or an expression.""") Expression field, Configuration configuration) {
         super(source, field, configuration, Case.UPPER);
     }