[Backport 2.x] Flat object field should delegate to keyword field for most query types

CHANGELOG.md

@@ -22,6 +22,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - New `phone` & `phone-search` analyzer + tokenizer ([#15915](https://github.com/opensearch-project/OpenSearch/pull/15915))
 - Add _list/indices API as paginated alternate to _cat/indices ([#14718](https://github.com/opensearch-project/OpenSearch/pull/14718))
 - Add changes to block calls in cat shards, indices and segments based on dynamic limit settings ([#15986](https://github.com/opensearch-project/OpenSearch/pull/15986))
+- Flat object field use IndexOrDocValuesQuery to optimize query ([#14383](https://github.com/opensearch-project/OpenSearch/issues/14383))
 
 ### Dependencies
 - Bump `org.apache.logging.log4j:log4j-core` from 2.23.1 to 2.24.0 ([#15858](https://github.com/opensearch-project/OpenSearch/pull/15858))

rest-api-spec/src/main/resources/rest-api-spec/test/index/90_flat_object.yml

@@ -671,38 +671,6 @@ teardown:
   - match: { error.root_cause.0.reason: "Mapping definition for [data] has unsupported parameters:  [analyzer : standard]"}
   - match: { status: 400 }
 
-  # Wildcard Query with dot path.
-  - do:
-      catch: bad_request
-      search:
-        body: {
-          _source: true,
-          query: {
-            "wildcard": {
-              "catalog.title": "Mock*"
-            }
-          }
-        }
-  - match: { error.root_cause.0.type: "query_shard_exception" }
-  - match: { error.root_cause.0.reason: "Can only use wildcard queries on keyword and text fields - not on [catalog.title] which is of type [flat_object]"}
-  - match: { status: 400 }
-
-  # Wildcard Query without dot path.
-  - do:
-      catch: bad_request
-      search:
-        body: {
-          _source: true,
-          query: {
-            "wildcard": {
-              "catalog": "Mock*"
-            }
-          }
-        }
-  - match: { error.root_cause.0.type: "query_shard_exception" }
-  - match: { error.root_cause.0.reason: "Can only use wildcard queries on keyword and text fields - not on [catalog] which is of type [flat_object]" }
-  - match: { status: 400 }
-
   # Aggregation and Match Query with dot path.
   - do:
       catch: bad_request