Merge branch '8.17' into release-notes-8-17-9

Author: charlotte-hoblik

docs/changelog/130776.yaml

@@ -0,0 +1,6 @@
+pr: 130776
+summary: Fix msearch request parsing when index expression is null
+area: Search
+type: bug
+issues:
+ - 129631

docs/reference/esql/esql-limitations.asciidoc

@@ -229,3 +229,17 @@ the <<esql-mv-functions,multivalue functions>>.
 === Kibana limitations
 
 include::esql-kibana.asciidoc[tag=limitations]
+
+[discrete]
+[[esql-known-issues]]
+== Known issues
+
+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.
+
+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
+

docs/reference/release-notes/8.16.0.asciidoc

@@ -517,3 +517,13 @@ Snapshot/Restore::
 {esql}::
 
 * Some valid queries using an `ENRICH` command can fail when a match field is used that is absent from some indices or shards, either with a 500 status code due to `NullPointerException` or `ClassCastException` or with a 400 status code and `IllegalArgumentException`. This is fixed in {es-pull}126187[#126187].
+
+* 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.
+
+  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
+

server/src/main/java/org/elasticsearch/common/xcontent/support/XContentMapValues.java

@@ -567,6 +567,9 @@ public static Map<String, Object> nodeMapValue(Object node, String desc) {
      * Otherwise the node is treated as a comma-separated string.
      */
     public static String[] nodeStringArrayValue(Object node) {
+        if (node == null) {
+            throw new ElasticsearchParseException("Expected a list of strings but got null");
+        }
         if (isArray(node)) {
             List<?> list = (List<?>) node;
             String[] arr = new String[list.size()];

server/src/test/java/org/elasticsearch/action/search/MultiSearchRequestTests.java

@@ -9,6 +9,7 @@
 
 package org.elasticsearch.action.search;
 
+import org.elasticsearch.ElasticsearchParseException;
 import org.elasticsearch.action.support.IndicesOptions;
 import org.elasticsearch.common.CheckedBiConsumer;
 import org.elasticsearch.common.Strings;
@@ -594,6 +595,14 @@ public void testFailOnExtraCharacters() throws IOException {
         }
     }
 
+    public void testNullIndex() throws IOException {
+        ElasticsearchParseException e = expectThrows(ElasticsearchParseException.class, () -> parseMultiSearchRequestFromString("""
+            {"index": null}
+            { "query": {"match_all": {}}}
+            """, null));
+        assertThat(e.getMessage(), containsString("Expected a list of strings but got null"));
+    }
+
     private static MultiSearchRequest mutate(MultiSearchRequest searchRequest) throws IOException {
         MultiSearchRequest mutation = copyRequest(searchRequest);
         List<CheckedRunnable<IOException>> mutators = new ArrayList<>();

x-pack/plugin/async-search/build.gradle

@@ -1,3 +1,5 @@
+import org.elasticsearch.gradle.testclusters.StandaloneRestIntegTestTask
+
 apply plugin: 'elasticsearch.internal-es-plugin'
 apply plugin: 'elasticsearch.internal-cluster-test'
 apply plugin: 'elasticsearch.internal-java-rest-test'
@@ -34,3 +36,8 @@ restResources {
     include '_common', 'indices', 'index', 'async_search'
   }
 }
+
+tasks.withType(StandaloneRestIntegTestTask).configureEach {
+  def isSnapshot = buildParams.snapshotBuild
+  it.onlyIf("snapshot build") { isSnapshot }
+}