Handle MultiMatch function

Author: julian-elastic

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

@@ -64,7 +64,6 @@
 import static org.elasticsearch.xpack.esql.core.expression.TypeResolutions.ParamOrdinal.THIRD;
 import static org.elasticsearch.xpack.esql.core.expression.TypeResolutions.isMapExpression;
 import static org.elasticsearch.xpack.esql.core.expression.TypeResolutions.isNotNull;
-import static org.elasticsearch.xpack.esql.core.expression.TypeResolutions.isNotNullAndFoldable;
 import static org.elasticsearch.xpack.esql.core.expression.TypeResolutions.isType;
 import static org.elasticsearch.xpack.esql.core.type.DataType.BOOLEAN;
 import static org.elasticsearch.xpack.esql.core.type.DataType.DATETIME;
@@ -78,6 +77,7 @@
 import static org.elasticsearch.xpack.esql.core.type.DataType.TEXT;
 import static org.elasticsearch.xpack.esql.core.type.DataType.UNSIGNED_LONG;
 import static org.elasticsearch.xpack.esql.core.type.DataType.VERSION;
+import static org.elasticsearch.xpack.esql.expression.function.FunctionUtils.resolveTypeQuery;
 
 /**
  * Full text function that performs a {@link org.elasticsearch.xpack.esql.querydsl.query.MultiMatchQuery} .
@@ -415,13 +415,21 @@ private TypeResolution resolveOptions() {
     }
 
     private TypeResolution resolveQuery() {
-        return isType(
+        TypeResolution result = isType(
             query(),
             QUERY_DATA_TYPES::contains,
             sourceText(),
             FIRST,
             "keyword, boolean, date, date_nanos, double, integer, ip, long, unsigned_long, version"
-        ).and(isNotNullAndFoldable(query(), sourceText(), FIRST));
+        ).and(isNotNull(query(), sourceText(), FIRST));
+        if (result.unresolved()) {
+            return result;
+        }
+        result = resolveTypeQuery(query(), sourceText());
+        if (result.equals(TypeResolution.TYPE_RESOLVED) == false) {
+            return result;
+        }
+        return TypeResolution.TYPE_RESOLVED;
     }
 
     @Override

x-pack/plugin/src/yamlRestTest/resources/rest-api-spec/test/esql/230_folding.yml

@@ -202,3 +202,42 @@ Foldable query using PHRASE_MATCH on name but with non-foldable expression:
             | LIMIT 5
   - match: { error.type: "verification_exception" }
   - contains: { error.reason: "Query must be a valid string in [MATCH_PHRASE(name, CONCAT(\"Bob \", name))], found [CONCAT(\"Bob \", name)]" }
+
+---
+
+Foldable query using MULTI_MATCH on name:
+  - do:
+      esql.query:
+        body:
+          query: |
+            FROM employees
+            | WHERE MULTI_MATCH(CONCAT("Bob ", "Johnson"), name)
+            | KEEP hire_date, salary, salary_change, salary_change_long, name
+            | LIMIT 5
+  - match: { columns.0.name: "hire_date" }
+  - match: { columns.1.name: "salary" }
+  - match: { columns.2.name: "salary_change" }
+  - match: { columns.3.name: "salary_change_long" }
+  - match: { columns.4.name: "name" }
+  - length: { values: 1 }
+  - match: { values.0.0: "2021-01-01T00:00:00.000Z" }
+  - match: { values.0.1: 60000 }
+  - match: { values.0.2: 200.5 }
+  - match: { values.0.3: 200 }
+  - match: { values.0.4: "Bob Johnson" }
+
+---
+
+Foldable query using MULTI_MATCH on name but with non-foldable expression:
+  - do:
+      catch: bad_request
+      esql.query:
+        body:
+          query: |
+            FROM employees
+            | WHERE MULTI_MATCH(CONCAT("Bob ", name), name)
+            | KEEP hire_date, salary, salary_change, salary_change_long, name
+            | LIMIT 5
+  - match: { error.type: "verification_exception" }
+  - contains: { error.reason: "Query must be a valid string in [MULTI_MATCH(CONCAT(\"Bob \", name), name)], found [CONCAT(\"Bob \", name)]" }
+