Merge branch 'main' into esql-test-cleanup

Author: nik9000

docs/changelog/131032.yaml

@@ -0,0 +1,5 @@
+pr: 131032
+summary: "Fix: `GET _synonyms` returns synonyms with empty rules"
+area: Relevance
+type: bug
+issues: []

docs/reference/query-languages/esql/limitations.md

@@ -250,3 +250,6 @@ Work around this limitation by converting the field to single value with one of
 * CSV export from Discover shows no more than 10,000 rows. This limit only applies to the number of rows that are retrieved by the query and displayed in Discover. Queries and aggregations run on the full data set.
 * Querying many indices at once without any filters can cause an error in kibana which looks like `[esql] > Unexpected error from Elasticsearch: The content length (536885793) is bigger than the maximum allowed string (536870888)`. The response from {{esql}} is too long. Use [`DROP`](/reference/query-languages/esql/commands/processing-commands.md#esql-drop) or [`KEEP`](/reference/query-languages/esql/commands/processing-commands.md#esql-keep) to limit the number of fields returned.
 
+## Known issues [esql-known-issues]
+
+Refer to [Known issues](/release-notes/known-issues.md) for a list of known issues for {{esql}}.

docs/release-notes/known-issues.md

@@ -8,10 +8,19 @@ mapped_pages:
 Known issues are significant defects or limitations that may impact your implementation. These issues are actively being worked on and will be addressed in a future release. Review the Elasticsearch known issues to help you make informed decisions, such as upgrading to a new version.
 
 ## 9.0.3 [elasticsearch-9.0.3-known-issues]
-A bug in the merge scheduler in Elasticsearch 9.0.3 may prevent shards from closing when there isn’t enough disk space to complete a merge. As a result, operations such as closing or relocating an index may hang until sufficient disk space becomes available.
+* A bug in the merge scheduler in Elasticsearch 9.0.3 may prevent shards from closing when there isn’t enough disk space to complete a merge. As a result, operations such as closing or relocating an index may hang until sufficient disk space becomes available.
 To mitigate this issue, the disk space checker is disabled by default in 9.0.3 by setting `indices.merge.disk.check_interval` to `0` seconds. Manually enabling this setting is not recommended.
 
-This issue is planned to be fixed in future patch release [#129613](https://github.com/elastic/elasticsearch/pull/129613)
+  This issue is planned to be fixed in future patch release [#129613](https://github.com/elastic/elasticsearch/pull/129613)
+
+* A bug in the ES|QL STATS command may yield incorrect results. The bug only happens in very specific cases that follow this pattern: `STATS ... BY keyword1, keyword2`, i.e. the command must have exactly two grouping fields, both keywords, where the first field has high cardinality (more than 65k distinct values).
+
+  The bug is described in detail in [this issue](https://github.com/elastic/elasticsearch/issues/130644).
+  The problem was introduced in 8.16.0 and [fixed](https://github.com/elastic/elasticsearch/pull/130705) in 8.17.9, 8.18.7, 9.0.4.
+
+  Possible workarounds include:
+  * switching the order of the grouping keys (eg. `STATS ... BY keyword2, keyword1`, if the `keyword2` has a lower cardinality)
+  * reducing the grouping key cardinality, by filtering out values before STATS
 
 ## 9.0.0 [elasticsearch-9.0.0-known-issues]
 * Elasticsearch on Windows might fail to start, or might forbid some file-related operations, when referencing paths with a case different from the one stored by the filesystem. Windows treats paths as case-insensitive, but the filesystem stores them with case. Entitlements, the new security system used by Elasticsearch, treat all paths as case-sensitive, and can therefore prevent access to a path that should be accessible.
@@ -40,3 +49,12 @@ This issue will be fixed in a future patch release (see [PR #126990](https://git
      DELETE _index_template/.watches
      POST /_watcher/_start
      ```
+
+* A bug in the ES|QL STATS command may yield incorrect results. The bug only happens in very specific cases that follow this pattern: `STATS ... BY keyword1, keyword2`, i.e. the command must have exactly two grouping fields, both keywords, where the first field has high cardinality (more than 65k distinct values).
+
+  The bug is described in detail in [this issue](https://github.com/elastic/elasticsearch/issues/130644).
+  The problem was introduced in 8.16.0 and [fixed](https://github.com/elastic/elasticsearch/pull/130705) in 8.17.9, 8.18.7, 9.0.4.
+
+  Possible workarounds include:
+    * switching the order of the grouping keys (eg. `STATS ... BY keyword2, keyword1`, if the `keyword2` has a lower cardinality)
+    * reducing the grouping key cardinality, by filtering out values before STATS

muted-tests.yml

@@ -519,12 +519,6 @@ tests:
 - class: org.elasticsearch.xpack.esql.action.EsqlActionBreakerIT
   method: testTopNPushedToLucene
   issue: https://github.com/elastic/elasticsearch/issues/130505
-- class: org.elasticsearch.xpack.monitoring.exporter.http.HttpExporterTests
-  method: testExporterWithHostOnly
-  issue: https://github.com/elastic/elasticsearch/issues/130599
-- class: org.elasticsearch.xpack.monitoring.exporter.http.HttpExporterTests
-  method: testCreateRestClient
-  issue: https://github.com/elastic/elasticsearch/issues/130600
 - class: org.elasticsearch.xpack.esql.qa.multi_node.EsqlSpecIT
   method: test {match-operator.MatchWithMoreComplexDisjunctionAndConjunction SYNC}
   issue: https://github.com/elastic/elasticsearch/issues/130640
@@ -543,9 +537,6 @@ tests:
 - class: org.elasticsearch.xpack.esql.action.CrossClusterAsyncQueryStopIT
   method: testStopQueryLocal
   issue: https://github.com/elastic/elasticsearch/issues/121672
-- class: org.elasticsearch.xpack.esql.action.EsqlRemoteErrorWrapIT
-  method: testThatRemoteErrorsAreWrapped
-  issue: https://github.com/elastic/elasticsearch/issues/130794
 - class: org.elasticsearch.backwards.MixedClusterClientYamlTestSuiteIT
   method: test {p0=mtermvectors/10_basic/Tests catching other exceptions per item}
   issue: https://github.com/elastic/elasticsearch/issues/122414
@@ -567,6 +558,9 @@ tests:
 - class: org.elasticsearch.xpack.esql.action.EsqlActionBreakerIT
   method: testRowStatsProjectGroupByInt
   issue: https://github.com/elastic/elasticsearch/issues/131024
+- class: org.elasticsearch.common.util.concurrent.TaskExecutionTimeTrackingEsThreadPoolExecutorTests
+  method: testMaxQueueLatency
+  issue: https://github.com/elastic/elasticsearch/issues/131093
 
 # Examples:
 #

rest-api-spec/src/yamlRestTest/resources/rest-api-spec/test/synonyms/40_synonyms_sets_get.yml

@@ -157,3 +157,33 @@ setup:
 
   - match:
       count: 12
+
+---
+"Return empty rule set":
+  - requires:
+      cluster_features: [ synonyms_set.get.return_empty_synonym_sets ]
+      reason: "synonyms_set get api return empty synonym sets"
+
+  - do:
+      synonyms.put_synonym:
+        id: empty-synonyms
+        body:
+          synonyms_set: []
+
+  - do:
+      synonyms.get_synonyms_sets: {}
+
+  - match:
+      count: 4
+
+  - match:
+      results:
+        - synonyms_set: "empty-synonyms"
+          count: 0
+        - synonyms_set: "test-synonyms-1"
+          count: 3
+        - synonyms_set: "test-synonyms-2"
+          count: 1
+        - synonyms_set: "test-synonyms-3"
+          count: 2
+

server/src/main/java/module-info.java

@@ -429,6 +429,7 @@
             org.elasticsearch.index.mapper.MapperFeatures,
             org.elasticsearch.index.IndexFeatures,
             org.elasticsearch.search.SearchFeatures,
+            org.elasticsearch.synonyms.SynonymFeatures,
             org.elasticsearch.script.ScriptFeatures,
             org.elasticsearch.search.retriever.RetrieversFeatures,
             org.elasticsearch.action.admin.cluster.stats.ClusterStatsFeatures,

server/src/main/java/org/elasticsearch/synonyms/SynonymFeatures.java

@@ -0,0 +1,24 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the "Elastic License
+ * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
+ * Public License v 1"; you may not use this file except in compliance with, at
+ * your election, the "Elastic License 2.0", the "GNU Affero General Public
+ * License v3.0 only", or the "Server Side Public License, v 1".
+ */
+
+package org.elasticsearch.synonyms;
+
+import org.elasticsearch.features.FeatureSpecification;
+import org.elasticsearch.features.NodeFeature;
+
+import java.util.Set;
+
+public class SynonymFeatures implements FeatureSpecification {
+    private static final NodeFeature RETURN_EMPTY_SYNONYM_SETS = new NodeFeature("synonyms_set.get.return_empty_synonym_sets");
+
+    @Override
+    public Set<NodeFeature> getTestFeatures() {
+        return Set.of(RETURN_EMPTY_SYNONYM_SETS);
+    }
+}

server/src/main/java/org/elasticsearch/synonyms/SynonymsManagementAPIService.java

@@ -50,6 +50,9 @@
 import org.elasticsearch.indices.SystemIndexDescriptor;
 import org.elasticsearch.rest.RestStatus;
 import org.elasticsearch.search.aggregations.BucketOrder;
+import org.elasticsearch.search.aggregations.bucket.filter.Filters;
+import org.elasticsearch.search.aggregations.bucket.filter.FiltersAggregationBuilder;
+import org.elasticsearch.search.aggregations.bucket.filter.FiltersAggregator;
 import org.elasticsearch.search.aggregations.bucket.terms.Terms;
 import org.elasticsearch.search.aggregations.bucket.terms.TermsAggregationBuilder;
 import org.elasticsearch.search.builder.SearchSourceBuilder;
@@ -94,6 +97,8 @@ public class SynonymsManagementAPIService {
     private static final int MAX_SYNONYMS_SETS = 10_000;
     private static final String SYNONYM_RULE_ID_FIELD = SynonymRule.ID_FIELD.getPreferredName();
     private static final String SYNONYM_SETS_AGG_NAME = "synonym_sets_aggr";
+    private static final String RULE_COUNT_AGG_NAME = "rule_count";
+    private static final String RULE_COUNT_FILTER_KEY = "synonym_rules";
     private static final int SYNONYMS_INDEX_MAPPINGS_VERSION = 1;
     public static final int INDEX_SEARCHABLE_TIMEOUT_SECONDS = 30;
     private final int maxSynonymsSets;
@@ -185,27 +190,45 @@ private static XContentBuilder mappings() {
         }
     }
 
+    /**
+     * Returns all synonym sets with their rule counts, including empty synonym sets.
+     * @param from The index of the first synonym set to return
+     * @param size The number of synonym sets to return
+     * @param listener The listener to return the synonym sets to
+     */
     public void getSynonymsSets(int from, int size, ActionListener<PagedResult<SynonymSetSummary>> listener) {
+        BoolQueryBuilder synonymSetQuery = QueryBuilders.boolQuery()
+            .should(QueryBuilders.termQuery(OBJECT_TYPE_FIELD, SYNONYM_SET_OBJECT_TYPE))
+            .should(QueryBuilders.termQuery(OBJECT_TYPE_FIELD, SYNONYM_RULE_OBJECT_TYPE))
+            .minimumShouldMatch(1);
+
+        // Aggregation query to count only synonym rules (excluding synonym set objects)
+        FiltersAggregationBuilder ruleCountAggregation = new FiltersAggregationBuilder(
+            RULE_COUNT_AGG_NAME,
+            new FiltersAggregator.KeyedFilter(RULE_COUNT_FILTER_KEY, QueryBuilders.termQuery(OBJECT_TYPE_FIELD, SYNONYM_RULE_OBJECT_TYPE))
+        );
+
         client.prepareSearch(SYNONYMS_ALIAS_NAME)
             .setSize(0)
             // Retrieves aggregated synonym rules for each synonym set, excluding the synonym set object type
-            .setQuery(QueryBuilders.termQuery(OBJECT_TYPE_FIELD, SYNONYM_RULE_OBJECT_TYPE))
+            .setQuery(synonymSetQuery)
             .addAggregation(
                 new TermsAggregationBuilder(SYNONYM_SETS_AGG_NAME).field(SYNONYMS_SET_FIELD)
                     .order(BucketOrder.key(true))
                     .size(maxSynonymsSets)
+                    .subAggregation(ruleCountAggregation)
             )
             .setPreference(Preference.LOCAL.type())
             .execute(new ActionListener<>() {
                 @Override
                 public void onResponse(SearchResponse searchResponse) {
                     Terms termsAggregation = searchResponse.getAggregations().get(SYNONYM_SETS_AGG_NAME);
                     List<? extends Terms.Bucket> buckets = termsAggregation.getBuckets();
-                    SynonymSetSummary[] synonymSetSummaries = buckets.stream()
-                        .skip(from)
-                        .limit(size)
-                        .map(bucket -> new SynonymSetSummary(bucket.getDocCount(), bucket.getKeyAsString()))
-                        .toArray(SynonymSetSummary[]::new);
+                    SynonymSetSummary[] synonymSetSummaries = buckets.stream().skip(from).limit(size).map(bucket -> {
+                        Filters ruleCountFilters = bucket.getAggregations().get(RULE_COUNT_AGG_NAME);
+                        Filters.Bucket ruleCountBucket = ruleCountFilters.getBucketByKey(RULE_COUNT_FILTER_KEY);
+                        return new SynonymSetSummary(ruleCountBucket.getDocCount(), bucket.getKeyAsString());
+                    }).toArray(SynonymSetSummary[]::new);
 
                     listener.onResponse(new PagedResult<>(buckets.size(), synonymSetSummaries));
                 }

server/src/main/resources/META-INF/services/org.elasticsearch.features.FeatureSpecification

@@ -14,6 +14,7 @@ org.elasticsearch.rest.action.admin.cluster.GetSnapshotsFeatures
 org.elasticsearch.index.IndexFeatures
 org.elasticsearch.index.mapper.MapperFeatures
 org.elasticsearch.search.SearchFeatures
+org.elasticsearch.synonyms.SynonymFeatures
 org.elasticsearch.search.retriever.RetrieversFeatures
 org.elasticsearch.script.ScriptFeatures
 org.elasticsearch.cluster.routing.RoutingFeatures

x-pack/plugin/esql/compute/gen/src/main/java/org/elasticsearch/compute/gen/GroupingAggregatorImplementer.java

@@ -200,7 +200,7 @@ private TypeSpec type() {
         builder.addMethod(ctor());
         builder.addMethod(intermediateStateDesc());
         builder.addMethod(intermediateBlockCount());
-        builder.addMethod(prepareProcessPage());
+        builder.addMethod(prepareProcessRawInputPage());
         for (ClassName groupIdClass : GROUP_IDS_CLASSES) {
             builder.addMethod(addRawInputLoop(groupIdClass, blockType(aggParam.type())));
             builder.addMethod(addRawInputLoop(groupIdClass, vectorType(aggParam.type())));
@@ -315,10 +315,10 @@ private MethodSpec intermediateBlockCount() {
     }
 
     /**
-     * Prepare to process a single page of results.
+     * Prepare to process a single raw input page.
      */
-    private MethodSpec prepareProcessPage() {
-        MethodSpec.Builder builder = MethodSpec.methodBuilder("prepareProcessPage");
+    private MethodSpec prepareProcessRawInputPage() {
+        MethodSpec.Builder builder = MethodSpec.methodBuilder("prepareProcessRawInputPage");
         builder.addAnnotation(Override.class).addModifiers(Modifier.PUBLIC).returns(GROUPING_AGGREGATOR_FUNCTION_ADD_INPUT);
         builder.addParameter(SEEN_GROUP_IDS, "seenGroupIds").addParameter(PAGE, "page");