Relax translog assertion for inference fields (#121092) (#121107)

The inference fields are synthesized from doc_values, regardless of
whether the synthetic source is enabled. This change relaxes the
translog assertions, allowing inference fields in the same way as we did
with the synthetic source.

Relates #120045

Closes #120979
Closes #121007
Closes #120980
Closes #120975

Author: dnhatn

muted-tests.yml

@@ -456,34 +456,20 @@ tests:
 - class: org.elasticsearch.xpack.test.rest.XPackRestIT
   method: test {p0=snapshot/20_operator_privileges_disabled/Operator only settings can be set and restored by non-operator user when operator privileges is disabled}
   issue: https://github.com/elastic/elasticsearch/issues/120973
-- class: org.elasticsearch.xpack.inference.action.filter.ShardBulkInferenceActionFilterIT
-  method: testBulkOperations {p0=false}
-  issue: https://github.com/elastic/elasticsearch/issues/120975
 - class: org.elasticsearch.packaging.test.DockerTests
   issue: https://github.com/elastic/elasticsearch/issues/120978
-- class: org.elasticsearch.xpack.esql.qa.multi_node.RestEsqlIT
-  method: testInternalRange {ASYNC}
-  issue: https://github.com/elastic/elasticsearch/issues/120979
-- class: org.elasticsearch.xpack.esql.qa.multi_node.RestEsqlIT
-  method: testWarningHeadersOnFailedConversions {ASYNC}
-  issue: https://github.com/elastic/elasticsearch/issues/120980
 - class: org.elasticsearch.xpack.security.authc.jwt.JwtRealmSingleNodeTests
   method: testActivateProfileForJWT
   issue: https://github.com/elastic/elasticsearch/issues/120983
 - class: org.elasticsearch.xpack.security.profile.ProfileIntegTests
   method: testProfileIndexAutoCreation
   issue: https://github.com/elastic/elasticsearch/issues/120987
-- class: org.elasticsearch.xpack.esql.qa.multi_node.RestEsqlIT
-  method: testOutOfRangeComparisons {ASYNC}
-  issue: https://github.com/elastic/elasticsearch/issues/121007
 - class: org.elasticsearch.xpack.security.authc.service.ServiceAccountIT
   method: testAuthenticateShouldNotFallThroughInCaseOfFailure
   issue: https://github.com/elastic/elasticsearch/issues/120902
 - class: org.elasticsearch.xpack.security.FileSettingsRoleMappingsRestartIT
   method: testReservedStatePersistsOnRestart
   issue: https://github.com/elastic/elasticsearch/issues/120923
-- class: org.elasticsearch.xpack.esql.qa.multi_node.RestEsqlIT
-  issue: https://github.com/elastic/elasticsearch/issues/120948
 - class: org.elasticsearch.datastreams.DataStreamsClientYamlTestSuiteIT
   method: test {p0=data_stream/140_data_stream_aliases/Create data stream alias}
   issue: https://github.com/elastic/elasticsearch/issues/120920

server/src/main/java/org/elasticsearch/index/engine/TranslogDirectoryReader.java

@@ -96,7 +96,7 @@ static DirectoryReader create(
             // When using synthetic source, the translog operation must always be reindexed into an in-memory Lucene to ensure consistent
             // output for realtime-get operations. However, this can degrade the performance of realtime-get and update operations.
             // If slight inconsistencies in realtime-get operations are acceptable, the translog operation can be reindexed lazily.
-            if (mappingLookup.isSourceSynthetic()) {
+            if (mappingLookup.isSourceSynthetic() || mappingLookup.inferenceFields().isEmpty() == false) {
                 onSegmentCreated.run();
                 leafReader = createInMemoryReader(shardId, engineConfig, directory, documentParser, mappingLookup, false, operation);
             } else {

server/src/main/java/org/elasticsearch/index/engine/TranslogOperationAsserter.java

@@ -38,7 +38,8 @@ public boolean assertSameIndexOperation(Translog.Index o1, Translog.Index o2) th
                 if (super.assertSameIndexOperation(o1, o2)) {
                     return true;
                 }
-                if (engineConfig.getIndexSettings().isRecoverySourceSyntheticEnabled()) {
+                if (engineConfig.getIndexSettings().isRecoverySourceSyntheticEnabled()
+                    || engineConfig.getMapperService().mappingLookup().inferenceFields().isEmpty() == false) {
                     return super.assertSameIndexOperation(synthesizeSource(engineConfig, o1), o2)
                         || super.assertSameIndexOperation(o1, synthesizeSource(engineConfig, o2));
                 }
@@ -60,26 +61,42 @@ static Translog.Index synthesizeSource(EngineConfig engineConfig, Translog.Index
                 TrivialQueryCachingPolicy.NEVER,
                 () -> {}
             );
-            try (
-                LuceneSyntheticSourceChangesSnapshot snapshot = new LuceneSyntheticSourceChangesSnapshot(
-                    engineConfig.getMapperService(),
-                    searcher,
-                    LuceneSyntheticSourceChangesSnapshot.DEFAULT_BATCH_SIZE,
-                    Integer.MAX_VALUE,
-                    op.seqNo(),
-                    op.seqNo(),
-                    true,
-                    false,
-                    engineConfig.getIndexSettings().getIndexVersionCreated()
-                )
-            ) {
+            try (var snapshot = newSnapshot(engineConfig, op, searcher);) {
                 final Translog.Operation normalized = snapshot.next();
                 assert normalized != null : "expected one operation; got zero";
                 return (Translog.Index) normalized;
             }
         }
     }
 
+    static Translog.Snapshot newSnapshot(EngineConfig engineConfig, Translog.Index op, Engine.Searcher searcher) throws IOException {
+        if (engineConfig.getIndexSettings().isRecoverySourceSyntheticEnabled()) {
+            return new LuceneSyntheticSourceChangesSnapshot(
+                engineConfig.getMapperService(),
+                searcher,
+                LuceneSyntheticSourceChangesSnapshot.DEFAULT_BATCH_SIZE,
+                Integer.MAX_VALUE,
+                op.seqNo(),
+                op.seqNo(),
+                true,
+                false,
+                engineConfig.getIndexSettings().getIndexVersionCreated()
+            );
+        } else {
+            return new LuceneChangesSnapshot(
+                engineConfig.getMapperService(),
+                searcher,
+                LuceneSyntheticSourceChangesSnapshot.DEFAULT_BATCH_SIZE,
+                op.seqNo(),
+                op.seqNo(),
+                true,
+                false,
+                false,
+                engineConfig.getIndexSettings().getIndexVersionCreated()
+            );
+        }
+    }
+
     public boolean assertSameIndexOperation(Translog.Index o1, Translog.Index o2) throws IOException {
         return Translog.Index.equalsWithoutAutoGeneratedTimestamp(o1, o2);
     }