working on getting the tests to pass in bwc mode

Author: julian-elastic

server/src/main/java/org/elasticsearch/TransportVersions.java

@@ -314,6 +314,7 @@ static TransportVersion def(int id) {
     public static final TransportVersion ML_INFERENCE_CUSTOM_SERVICE_INPUT_TYPE = def(9_105_0_00);
     public static final TransportVersion ML_INFERENCE_SAGEMAKER_ELASTIC = def(9_106_0_00);
     public static final TransportVersion SPARSE_VECTOR_FIELD_PRUNING_OPTIONS = def(9_107_0_00);
+    public static final TransportVersion ESQL_FIXED_INDEX_LIKE = def(9_108_0_00);
 
     /*
      * STOP! READ THIS FIRST! No, really,

server/src/main/java/org/elasticsearch/action/search/SearchShardsRequest.java

@@ -16,6 +16,7 @@
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.core.Nullable;
+import org.elasticsearch.index.query.MatchAllQueryBuilder;
 import org.elasticsearch.index.query.QueryBuilder;
 import org.elasticsearch.tasks.Task;
 import org.elasticsearch.tasks.TaskId;
@@ -77,7 +78,16 @@ public void writeTo(StreamOutput out) throws IOException {
         super.writeTo(out);
         out.writeStringArray(indices);
         indicesOptions.writeIndicesOptions(out);
-        out.writeOptionalNamedWriteable(query);
+        out.writeOptionalNamedWriteable(
+            query == null || query.supportsVersion(out.getTransportVersion()) ? query :
+                /*
+                 * The remote node doesn't support the query we're sending. If this were only
+                 * used for _search this could just fail, but for ESQL it's much more convenient
+                 * if it pretends that the query is MatchAll. ESQL will frequently be able to
+                 * perform the document filtering on the data node in its engine. Slowly.
+                 * But correctly.
+                 */
+                new MatchAllQueryBuilder());
         out.writeOptionalString(routing);
         out.writeOptionalString(preference);
         out.writeBoolean(allowPartialSearchResults);

server/src/main/java/org/elasticsearch/index/query/WildcardLikeQueryBuilder.java

@@ -215,6 +215,6 @@ protected boolean doEquals(WildcardLikeQueryBuilder other) {
 
     @Override
     public TransportVersion getMinimalSupportedVersion() {
-        return TransportVersions.ZERO;
+        return TransportVersions.ESQL_FIXED_INDEX_LIKE;
     }
 }

x-pack/plugin/esql/qa/server/multi-clusters/src/javaRestTest/java/org/elasticsearch/xpack/esql/ccq/MultiClustersIT.java

@@ -30,6 +30,7 @@
 import org.junit.rules.TestRule;
 
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -43,6 +44,9 @@
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.greaterThanOrEqualTo;
 import static org.hamcrest.Matchers.hasKey;
+import static org.hamcrest.Matchers.anyOf;
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.nullValue;
 
 @ThreadLeakFilters(filters = TestClustersThreadFilter.class)
 public class MultiClustersIT extends ESRestTestCase {
@@ -159,6 +163,36 @@ private Map<String, Object> runEsql(RestEsqlTestCase.RequestObjectBuilder reques
         }
     }
 
+    private <C, V> void assertResultMapForLike(
+        boolean includeCCSMetadata,
+        Map<String, Object> result,
+        C columns,
+        V values,
+        boolean remoteOnly,
+        boolean requireLikeListCapability
+    ) throws IOException {
+        List<String> requiredCapabilities = new ArrayList<>(List.of("like_on_index_fields"));
+        if (requireLikeListCapability) {
+            requiredCapabilities.add("like_list_on_index_fields");
+        }
+        // the feature is completely supported if both local and remote clusters support it
+        boolean isSupported = clusterHasCapability("POST", "/_query", List.of(), requiredCapabilities).orElse(false);
+        try (RestClient remoteClient = remoteClusterClient()) {
+            isSupported = isSupported
+                && clusterHasCapability(remoteClient, "POST", "/_query", List.of(), requiredCapabilities).orElse(false);
+        }
+
+        if (isSupported) {
+            assertResultMap(includeCCSMetadata, result, columns, values, remoteOnly);
+        } else {
+            logger.info("-->  skipping data check for like index test, cluster does not support like index feature");
+            // just verify that we did not get a partial result
+            var clusters = result.get("_clusters");
+            var reason = "unexpected partial results" + (clusters != null ? ": _clusters=" + clusters : "");
+            assertThat(reason, result.get("is_partial"), anyOf(nullValue(), is(false)));
+        }
+    }
+
     private <C, V> void assertResultMap(boolean includeCCSMetadata, Map<String, Object> result, C columns, V values, boolean remoteOnly) {
         MapMatcher mapMatcher = getResultMatcher(
             ccsMetadataAvailable(),
@@ -385,7 +419,7 @@ public void testLikeIndex() throws Exception {
         var values = List.of(List.of(remoteDocs.size(), REMOTE_CLUSTER_NAME + ":" + remoteIndex));
         String resultString = Strings.toString(JsonXContent.contentBuilder().prettyPrint().map(result));
         System.out.println(resultString);
-        assertResultMap(includeCCSMetadata, result, columns, values, false);
+        assertResultMapForLike(includeCCSMetadata, result, columns, values, false, false);
     }
 
     public void testNotLikeIndex() throws Exception {
@@ -400,7 +434,7 @@ public void testNotLikeIndex() throws Exception {
         var values = List.of(List.of(localDocs.size(), localIndex));
         String resultString = Strings.toString(JsonXContent.contentBuilder().prettyPrint().map(result));
         System.out.println(resultString);
-        assertResultMap(includeCCSMetadata, result, columns, values, false);
+        assertResultMapForLike(includeCCSMetadata, result, columns, values, false, false);
     }
 
     public void testLikeListIndex() throws Exception {
@@ -415,7 +449,7 @@ public void testLikeListIndex() throws Exception {
         var values = List.of(List.of(remoteDocs.size(), REMOTE_CLUSTER_NAME + ":" + remoteIndex));
         String resultString = Strings.toString(JsonXContent.contentBuilder().prettyPrint().map(result));
         System.out.println(resultString);
-        assertResultMap(includeCCSMetadata, result, columns, values, false);
+        assertResultMapForLike(includeCCSMetadata, result, columns, values, false, true);
     }
 
     public void testNotLikeListIndex() throws Exception {
@@ -430,7 +464,7 @@ public void testNotLikeListIndex() throws Exception {
         var values = List.of(List.of(localDocs.size(), localIndex));
         String resultString = Strings.toString(JsonXContent.contentBuilder().prettyPrint().map(result));
         System.out.println(resultString);
-        assertResultMap(includeCCSMetadata, result, columns, values, false);
+        assertResultMapForLike(includeCCSMetadata, result, columns, values, false, true);
     }
 
     public void testRLikeIndex() throws Exception {
@@ -443,8 +477,7 @@ public void testRLikeIndex() throws Exception {
             """, includeCCSMetadata);
         var columns = List.of(Map.of("name", "c", "type", "long"), Map.of("name", "_index", "type", "keyword"));
         var values = List.of(List.of(remoteDocs.size(), REMOTE_CLUSTER_NAME + ":" + remoteIndex));
-
-        assertResultMap(includeCCSMetadata, result, columns, values, false);
+        assertResultMapForLike(includeCCSMetadata, result, columns, values, false, false);
     }
 
     public void testNotRLikeIndex() throws Exception {
@@ -457,8 +490,7 @@ public void testNotRLikeIndex() throws Exception {
             """, includeCCSMetadata);
         var columns = List.of(Map.of("name", "c", "type", "long"), Map.of("name", "_index", "type", "keyword"));
         var values = List.of(List.of(localDocs.size(), localIndex));
-
-        assertResultMap(includeCCSMetadata, result, columns, values, false);
+        assertResultMapForLike(includeCCSMetadata, result, columns, values, false, false);
     }
 
     private RestClient remoteClusterClient() throws IOException {

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/action/EsqlCapabilities.java

@@ -1215,7 +1215,11 @@ public enum Cap {
         /**
          * (Re)Added EXPLAIN command
          */
-        EXPLAIN(Build.current().isSnapshot());
+        EXPLAIN(Build.current().isSnapshot()),
+        /**
+         * Support improved behavior for LIKE operator when used with index fields.
+         */
+        LIKE_ON_INDEX_FIELDS;
 
         private final boolean enabled;