Accept text field type for knn

Author: carlosdelest

x-pack/plugin/esql-core/src/main/java/org/elasticsearch/xpack/esql/core/expression/Expression.java

@@ -55,6 +55,10 @@ public TypeResolution and(TypeResolution other) {
             return failed ? this : other;
         }
 
+        public TypeResolution or(TypeResolution other) {
+            return failed ? other : this;
+        }
+
         public TypeResolution and(Supplier<TypeResolution> other) {
             return failed ? this : other.get();
         }

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

@@ -67,10 +67,14 @@
 import static org.elasticsearch.xpack.esql.core.type.DataType.DENSE_VECTOR;
 import static org.elasticsearch.xpack.esql.core.type.DataType.FLOAT;
 import static org.elasticsearch.xpack.esql.core.type.DataType.INTEGER;
+import static org.elasticsearch.xpack.esql.core.type.DataType.KEYWORD;
+import static org.elasticsearch.xpack.esql.core.type.DataType.TEXT;
 import static org.elasticsearch.xpack.esql.expression.Foldables.TypeResolutionValidator.forPreOptimizationValidation;
 import static org.elasticsearch.xpack.esql.expression.Foldables.resolveTypeQuery;
 
 public class Knn extends FullTextFunction implements OptionalArgument, VectorFunction, PostAnalysisPlanVerificationAware {
+
+    private static final String[] ACCEPTED_FIELD_TYPES = { "dense_vector", "semantic_text" };
     private final Logger log = LogManager.getLogger(getClass());
 
     public static final NamedWriteableRegistry.Entry ENTRY = new NamedWriteableRegistry.Entry(Expression.class, "Knn", Knn::readFrom);
@@ -209,7 +213,11 @@ protected TypeResolution resolveParams() {
     }
 
     private TypeResolution resolveField() {
-        return isNotNull(field(), sourceText(), FIRST).and(isType(field(), dt -> dt == DENSE_VECTOR, sourceText(), FIRST, "dense_vector"));
+        return isNotNull(field(), sourceText(), FIRST).and(
+            isType(field(), dt -> dt == TEXT, sourceText(), FIRST, ACCEPTED_FIELD_TYPES).or(
+                isType(field(), dt -> dt == DENSE_VECTOR, sourceText(), FIRST, ACCEPTED_FIELD_TYPES)
+            )
+        );
     }
 
     private TypeResolution resolveQuery() {