Update error message when lucene max document limit is breached

CHANGELOG.md

@@ -149,6 +149,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Disable concurrent aggs for Diversified Sampler and Sampler aggs ([#11087](https://github.com/opensearch-project/OpenSearch/issues/11087))
 - Made leader/follower check timeout setting dynamic ([#10528](https://github.com/opensearch-project/OpenSearch/pull/10528))
 - Improve boolean parsing performance ([#11308](https://github.com/opensearch-project/OpenSearch/pull/11308))
+- Change error message when per shard document limit is breached ([#11312](https://github.com/opensearch-project/OpenSearch/pull/11312))
 
 ### Deprecated
 

server/src/internalClusterTest/java/org/opensearch/index/engine/MaxDocsLimitIT.java

@@ -36,6 +36,8 @@
 import org.opensearch.action.search.SearchResponse;
 import org.opensearch.cluster.metadata.IndexMetadata;
 import org.opensearch.common.settings.Settings;
+import org.opensearch.core.index.Index;
+import org.opensearch.core.index.shard.ShardId;
 import org.opensearch.core.rest.RestStatus;
 import org.opensearch.core.xcontent.MediaTypeRegistry;
 import org.opensearch.index.IndexSettings;
@@ -65,6 +67,7 @@
 public class MaxDocsLimitIT extends OpenSearchIntegTestCase {
 
     private static final AtomicInteger maxDocs = new AtomicInteger();
+    private static final ShardId shardId = new ShardId(new Index("test", "_na_"), 0);
 
     public static class TestEnginePlugin extends Plugin implements EnginePlugin {
         @Override
@@ -122,7 +125,10 @@ public void testMaxDocsLimit() throws Exception {
             IllegalArgumentException.class,
             () -> client().prepareDelete("test", "any-id").get()
         );
-        assertThat(deleteError.getMessage(), containsString("Number of documents in the index can't exceed [" + maxDocs.get() + "]"));
+        assertThat(
+            deleteError.getMessage(),
+            containsString("Number of documents in shard " + shardId + " exceeds the limit of [" + maxDocs.get() + "] documents per shard")
+        );
         client().admin().indices().prepareRefresh("test").get();
         SearchResponse searchResponse = client().prepareSearch("test")
             .setQuery(new MatchAllQueryBuilder())
@@ -208,7 +214,16 @@ static IndexingResult indexDocs(int numRequests, int numThreads) throws Exceptio
                         assertThat(resp.status(), equalTo(RestStatus.CREATED));
                     } catch (IllegalArgumentException e) {
                         numFailure.incrementAndGet();
-                        assertThat(e.getMessage(), containsString("Number of documents in the index can't exceed [" + maxDocs.get() + "]"));
+                        assertThat(
+                            e.getMessage(),
+                            containsString(
+                                "Number of documents in shard "
+                                    + shardId
+                                    + " exceeds the limit of ["
+                                    + maxDocs.get()
+                                    + "] documents per shard"
+                            )
+                        );
                     }
                 }
             });

server/src/main/java/org/opensearch/index/engine/InternalEngine.java

@@ -1412,7 +1412,9 @@ private Exception tryAcquireInFlightDocs(Operation operation, int addingDocs) {
         final long totalDocs = indexWriter.getPendingNumDocs() + inFlightDocCount.addAndGet(addingDocs);
         if (totalDocs > maxDocs) {
             releaseInFlightDocs(addingDocs);
-            return new IllegalArgumentException("Number of documents in the index can't exceed [" + maxDocs + "]");
+            return new IllegalArgumentException(
+                "Number of documents in shard " + shardId + " exceeds the limit of [" + maxDocs + "] documents per shard"
+            );
         } else {
             return null;
         }

server/src/test/java/org/opensearch/index/engine/InternalEngineTests.java

@@ -7801,7 +7801,9 @@ public void testMaxDocsOnPrimary() throws Exception {
                     assertNotNull(result.getFailure());
                     assertThat(
                         result.getFailure().getMessage(),
-                        containsString("Number of documents in the index can't exceed [" + maxDocs + "]")
+                        containsString(
+                            "Number of documents in shard " + shardId + " exceeds the limit of [" + maxDocs + "] documents per shard"
+                        )
                     );
                     assertThat(result.getSeqNo(), equalTo(UNASSIGNED_SEQ_NO));
                     assertThat(engine.getLocalCheckpointTracker().getMaxSeqNo(), equalTo(maxSeqNo));