rest compatibility check with search features

Author: tteofili

rest-api-spec/src/yamlRestTest/resources/rest-api-spec/test/search.vectors/80_dense_vector_indexed_by_default.yml

@@ -25,8 +25,43 @@ setup:
   - match: { test.mappings.properties.vector.dims: 5 }
   - match: { test.mappings.properties.vector.index: true }
   - match: { test.mappings.properties.vector.similarity: cosine }
+
+---
+"Indexed by default with specified similarity and index options":
+  - do:
+      indices.create:
+        index: test
+        body:
+          mappings:
+            properties:
+              vector:
+                type: dense_vector
+                dims: 5
+                similarity: dot_product
+                index_options:
+                  type: hnsw
+                  m: 32
+                  ef_construction: 200
+
+  - match: { acknowledged: true }
+
+  - do:
+      indices.get_mapping:
+        index: test
+
+  - match: { test.mappings.properties.vector.type: dense_vector }
+  - match: { test.mappings.properties.vector.dims: 5 }
+  - match: { test.mappings.properties.vector.index: true }
+  - match: { test.mappings.properties.vector.similarity: dot_product }
+  - match: { test.mappings.properties.vector.index_options.type: hnsw }
+  - match: { test.mappings.properties.vector.index_options.m: 32 }
+  - match: { test.mappings.properties.vector.index_options.ef_construction: 200 }
+  - match: { test.mappings.properties.vector.index_options.early_termination: null }
+
 ---
 "Indexed by default with specified similarity and index options":
+  - cluster_features: [ "search.vectors.mappers.expose_hnsw_early_termination" ]
+  - reason: "requires early termination for hnsw to be exposed"
   - do:
       indices.create:
         index: test
@@ -55,6 +90,7 @@ setup:
   - match: { test.mappings.properties.vector.index_options.type: hnsw }
   - match: { test.mappings.properties.vector.index_options.m: 32 }
   - match: { test.mappings.properties.vector.index_options.ef_construction: 200 }
+  - match: { test.mappings.properties.vector.index_options.early_termination: false }
 
 ---
 "Not indexed vector":

server/src/main/java/org/elasticsearch/search/SearchFeatures.java

@@ -32,6 +32,7 @@ public Set<NodeFeature> getFeatures() {
     public static final NodeFeature INT_SORT_FOR_INT_SHORT_BYTE_FIELDS = new NodeFeature("search.sort.int_sort_for_int_short_byte_fields");
     static final NodeFeature MULTI_MATCH_CHECKS_POSITIONS = new NodeFeature("search.multi.match.checks.positions");
     public static final NodeFeature BBQ_HNSW_DEFAULT_INDEXING = new NodeFeature("search.vectors.mappers.default_bbq_hnsw");
+    public static final NodeFeature EXPOSE_HNSW_EARLY_TERMINATION = new NodeFeature("search.vectors.mappers.expose_hnsw_early_termination");
 
     @Override
     public Set<NodeFeature> getTestFeatures() {
@@ -41,7 +42,8 @@ public Set<NodeFeature> getTestFeatures() {
             RESCORER_MISSING_FIELD_BAD_REQUEST,
             INT_SORT_FOR_INT_SHORT_BYTE_FIELDS,
             MULTI_MATCH_CHECKS_POSITIONS,
-            BBQ_HNSW_DEFAULT_INDEXING
+            BBQ_HNSW_DEFAULT_INDEXING,
+            EXPOSE_HNSW_EARLY_TERMINATION
         );
     }
 }