Register the KQL function in various places.

Author: afoucret

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

@@ -31,6 +31,7 @@
 import org.elasticsearch.xpack.esql.expression.function.aggregate.FilteredExpression;
 import org.elasticsearch.xpack.esql.expression.function.aggregate.Rate;
 import org.elasticsearch.xpack.esql.expression.function.fulltext.FullTextFunction;
+import org.elasticsearch.xpack.esql.expression.function.fulltext.Kql;
 import org.elasticsearch.xpack.esql.expression.function.fulltext.Match;
 import org.elasticsearch.xpack.esql.expression.function.fulltext.QueryString;
 import org.elasticsearch.xpack.esql.expression.function.grouping.GroupingFunction;
@@ -684,6 +685,14 @@ private static void checkFullTextQueryFunctions(LogicalPlan plan, Set<Failure> f
                 qsf -> "[" + qsf.functionName() + "] " + qsf.functionType(),
                 failures
             );
+            checkCommandsBeforeExpression(
+                plan,
+                condition,
+                Kql.class,
+                lp -> (lp instanceof Filter || lp instanceof OrderBy || lp instanceof EsRelation),
+                kqlFunc -> "[" + kqlFunc.functionName() + "] " + kqlFunc.functionType(),
+                failures
+            );
             checkCommandsBeforeExpression(
                 plan,
                 condition,

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

@@ -32,6 +32,7 @@
 import org.elasticsearch.xpack.esql.expression.function.aggregate.Top;
 import org.elasticsearch.xpack.esql.expression.function.aggregate.Values;
 import org.elasticsearch.xpack.esql.expression.function.aggregate.WeightedAvg;
+import org.elasticsearch.xpack.esql.expression.function.fulltext.Kql;
 import org.elasticsearch.xpack.esql.expression.function.fulltext.Match;
 import org.elasticsearch.xpack.esql.expression.function.fulltext.QueryString;
 import org.elasticsearch.xpack.esql.expression.function.grouping.Bucket;
@@ -406,7 +407,8 @@ private static FunctionDefinition[][] snapshotFunctions() {
                 // This is an experimental function and can be removed without notice.
                 def(Delay.class, Delay::new, "delay"),
                 def(Categorize.class, Categorize::new, "categorize"),
-                def(Rate.class, Rate::withUnresolvedTimestamp, "rate") } };
+                def(Rate.class, Rate::withUnresolvedTimestamp, "rate"),
+                def(Kql.class, Kql::new, "kql") } };
     }
 
     public EsqlFunctionRegistry snapshotRegistry() {

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/fulltext/FullTextFunction.java

@@ -9,13 +9,16 @@
 
 import org.apache.lucene.util.BytesRef;
 import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
+import org.elasticsearch.xpack.esql.action.EsqlCapabilities;
 import org.elasticsearch.xpack.esql.core.expression.Expression;
 import org.elasticsearch.xpack.esql.core.expression.Nullability;
 import org.elasticsearch.xpack.esql.core.expression.TypeResolutions;
 import org.elasticsearch.xpack.esql.core.expression.function.Function;
 import org.elasticsearch.xpack.esql.core.tree.Source;
 import org.elasticsearch.xpack.esql.core.type.DataType;
 
+import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 import static org.elasticsearch.common.logging.LoggerMessageFormat.format;
@@ -30,7 +33,13 @@
  */
 public abstract class FullTextFunction extends Function {
     public static List<NamedWriteableRegistry.Entry> getNamedWriteables() {
-        return List.of(QueryString.ENTRY, Match.ENTRY);
+        List<NamedWriteableRegistry.Entry> writeables = new ArrayList<>(List.of(QueryString.ENTRY, Match.ENTRY));
+
+        if (EsqlCapabilities.Cap.KQL_FUNCTION.isEnabled()) {
+            writeables.add(Kql.ENTRY);
+        }
+
+        return Collections.unmodifiableList(writeables);
     }
 
     private final Expression query;

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/optimizer/rules/physical/local/PushFiltersToSource.java

@@ -31,8 +31,8 @@
 import org.elasticsearch.xpack.esql.core.type.DataType;
 import org.elasticsearch.xpack.esql.core.util.CollectionUtils;
 import org.elasticsearch.xpack.esql.core.util.Queries;
+import org.elasticsearch.xpack.esql.expression.function.fulltext.FullTextFunction;
 import org.elasticsearch.xpack.esql.expression.function.fulltext.Match;
-import org.elasticsearch.xpack.esql.expression.function.fulltext.QueryString;
 import org.elasticsearch.xpack.esql.expression.function.scalar.ip.CIDRMatch;
 import org.elasticsearch.xpack.esql.expression.function.scalar.spatial.BinarySpatialFunction;
 import org.elasticsearch.xpack.esql.expression.function.scalar.spatial.SpatialRelatesFunction;
@@ -255,10 +255,10 @@ static boolean canPushToSource(Expression exp, LucenePushdownPredicates lucenePu
             return canPushSpatialFunctionToSource(spatial, lucenePushdownPredicates);
         } else if (exp instanceof StringQueryPredicate) {
             return true;
-        } else if (exp instanceof QueryString) {
-            return true;
         } else if (exp instanceof Match mf) {
             return mf.field() instanceof FieldAttribute && DataType.isString(mf.field().dataType());
+        } else if (exp instanceof FullTextFunction) {
+            return true;
         }
         return false;
     }

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/planner/EsqlExpressionTranslators.java

@@ -23,6 +23,7 @@
 import org.elasticsearch.xpack.esql.core.planner.ExpressionTranslator;
 import org.elasticsearch.xpack.esql.core.planner.ExpressionTranslators;
 import org.elasticsearch.xpack.esql.core.planner.TranslatorHandler;
+import org.elasticsearch.xpack.esql.core.querydsl.query.KqlQuery;
 import org.elasticsearch.xpack.esql.core.querydsl.query.MatchAll;
 import org.elasticsearch.xpack.esql.core.querydsl.query.MatchQuery;
 import org.elasticsearch.xpack.esql.core.querydsl.query.NotQuery;
@@ -34,6 +35,7 @@
 import org.elasticsearch.xpack.esql.core.tree.Source;
 import org.elasticsearch.xpack.esql.core.type.DataType;
 import org.elasticsearch.xpack.esql.core.util.Check;
+import org.elasticsearch.xpack.esql.expression.function.fulltext.Kql;
 import org.elasticsearch.xpack.esql.expression.function.fulltext.Match;
 import org.elasticsearch.xpack.esql.expression.function.fulltext.QueryString;
 import org.elasticsearch.xpack.esql.expression.function.scalar.ip.CIDRMatch;
@@ -90,6 +92,7 @@ public final class EsqlExpressionTranslators {
         new ExpressionTranslators.MultiMatches(),
         new MatchFunctionTranslator(),
         new QueryStringFunctionTranslator(),
+        new KqlFunctionTranslator(),
         new Scalars()
     );
 
@@ -539,4 +542,11 @@ protected Query asQuery(QueryString queryString, TranslatorHandler handler) {
             return new QueryStringQuery(queryString.source(), queryString.queryAsText(), Map.of(), null);
         }
     }
+
+    public static class KqlFunctionTranslator extends ExpressionTranslator<Kql> {
+        @Override
+        protected Query asQuery(Kql kqlFunction, TranslatorHandler handler) {
+            return new KqlQuery(kqlFunction.source(), kqlFunction.queryAsText());
+        }
+    }
 }