ES|QL Empty index resolution

docs/changelog/135601.yaml

@@ -0,0 +1,12 @@
+pr: 135601
+summary: ES|QL Empty index resolution
+area: ES|QL
+type: breaking
+issues: []
+breaking:
+ title: ES|QL Empty index resolution
+ area: ES|QL
+ details: Changes index resolution so that `FROM empty*` resolves to empty set of indices (opposed to error today)
+ and becomes consistent with `GET /empty*/_search`.
+ impact: Makes a valid query check a bit more permissive in case when pattern is resolved to empty set of indices.
+ notable: false

x-pack/plugin/esql/qa/server/src/main/java/org/elasticsearch/xpack/esql/qa/rest/RequestIndexFilteringTestCase.java

@@ -206,11 +206,6 @@ public void testIndicesDontExist() throws IOException {
  assertThat(e.getMessage(), containsString("verification_exception"));
  assertThat(e.getMessage(), anyOf(containsString("Unknown index [foo]"), containsString("Unknown index [remote_cluster:foo]")));
 
- e = expectThrows(ResponseException.class, () -> runEsql(timestampFilter("gte", "2020-01-01").query(from("foo*"))));
- assertEquals(400, e.getResponse().getStatusLine().getStatusCode());
- assertThat(e.getMessage(), containsString("verification_exception"));
- assertThat(e.getMessage(), anyOf(containsString("Unknown index [foo*]"), containsString("Unknown index [remote_cluster:foo*]")));
-
  e = expectThrows(ResponseException.class, () -> runEsql(timestampFilter("gte", "2020-01-01").query("FROM foo, test1")));
  assertEquals(404, e.getResponse().getStatusLine().getStatusCode());
  assertThat(e.getMessage(), containsString("index_not_found_exception"));

x-pack/plugin/esql/src/internalClusterTest/java/org/elasticsearch/xpack/esql/plugin/IndexResolutionIT.java

@@ -112,23 +112,20 @@ public void testResolvesExclusionPattern() {
  assertOk(response);
  assertResultConcreteIndices(response, "index-1");// excludes pattern from pattern
  }
- expectThrows(
- VerificationException.class,
- containsString("Unknown index [index-*,-*]"),
- () -> run(syncEsqlQueryRequest().query("FROM index-*,-* METADATA _index")) // exclude all resolves to empty
- );
+ try (var response = run(syncEsqlQueryRequest().query("FROM index-*,-* METADATA _index"))) {
+ assertOk(response);
+ assertResultConcreteIndices(response);// exclude all resolves to empty
+ }
  }
 
- public void testDoesNotResolveEmptyPattern() {
+ public void testResolveEmptyPattern() {
  assertAcked(client().admin().indices().prepareCreate("data"));
  indexRandom(true, "data", 1);
 
- expectThrows(
- VerificationException.class,
- containsString("Unknown index [index-*]"),
- () -> run(syncEsqlQueryRequest().query("FROM index-* METADATA _index"))
- );
-
+ try (var response = run(syncEsqlQueryRequest().query("FROM index-* METADATA _index"))) {
+ assertOk(response);
+ assertResultConcreteIndices(response);
+ }
  try (var response = run(syncEsqlQueryRequest().query("FROM data,index-* METADATA _index"))) {
  assertOk(response);
  assertResultConcreteIndices(response, "data");

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/index/IndexResolution.java

@@ -41,6 +41,10 @@ public static IndexResolution invalid(String invalid) {
  return new IndexResolution(null, invalid, Set.of(), Map.of());
  }
 
+ public static IndexResolution empty(String indexPattern) {
+ return IndexResolution.valid(new EsIndex(indexPattern, Map.of(), Map.of()));
+ }
+
  public static IndexResolution notFound(String name) {
  Objects.requireNonNull(name, "name must not be null");
  return invalid("Unknown index [" + name + "]");

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/session/EsqlSession.java

@@ -531,6 +531,10 @@ private PreAnalysisResult receiveLookupIndexResolution(
  // If the index resolution is invalid, don't bother with the rest of the analysis
  return result.addLookupIndexResolution(index, lookupIndexResolution);
  }
+ if (lookupIndexResolution.get().concreteIndices().isEmpty()) {
+ // require non empty lookup index
+ return result.addLookupIndexResolution(index, IndexResolution.notFound(lookupIndexResolution.get().name()));
+ }
  if (executionInfo.getClusters().isEmpty() || executionInfo.isCrossClusterSearch() == false) {
  // Local only case, still do some checks, since we moved analysis checks here
  if (lookupIndexResolution.get().indexNameWithModes().isEmpty()) {
@@ -696,9 +700,7 @@ private void preAnalyzeMainIndices(
  String indexExpressionToResolve = EsqlCCSUtils.createIndexExpressionFromAvailableClusters(executionInfo);
  if (indexExpressionToResolve.isEmpty()) {
  // if this was a pure remote CCS request (no local indices) and all remotes are offline, return an empty IndexResolution
- listener.onResponse(
- result.withIndices(IndexResolution.valid(new EsIndex(preAnalysis.indexPattern().indexPattern(), Map.of(), Map.of())))
- );
+ listener.onResponse(result.withIndices(IndexResolution.empty(preAnalysis.indexPattern().indexPattern())));
  } else {
  indexResolver.resolveAsMergedMapping(
  indexExpressionToResolve,

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/session/IndexResolver.java

@@ -106,7 +106,7 @@ public static IndexResolution mergedMappings(String indexPattern, FieldsInfo fie
  assert ThreadPool.assertCurrentThreadPool(ThreadPool.Names.SEARCH_COORDINATION); // too expensive to run this on a transport worker
  int numberOfIndices = fieldsInfo.caps.getIndexResponses().size();
  if (numberOfIndices == 0) {
- return IndexResolution.notFound(indexPattern);
+ return IndexResolution.empty(indexPattern);
  }
 
  // For each field name, store a list of the field caps responses from each index