[GitHub] [kafka] dengziming commented on a diff in pull request #13845: KAFKA-15078; KRaft leader replys with snapshot for offset 0

["dengziming (via GitHub)" <gi...@apache.org>]

dengziming commented on code in PR #13845:
URL: https://github.com/apache/kafka/pull/13845#discussion_r1228931662


##########
raft/src/main/java/org/apache/kafka/raft/KafkaRaftClient.java:
##########
@@ -1017,7 +1017,16 @@ private FetchResponseData tryCompleteFetchRequest(
             long fetchOffset = request.fetchOffset();
             int lastFetchedEpoch = request.lastFetchedEpoch();
             LeaderState<T> state = quorum.leaderStateOrThrow();
-            ValidOffsetAndEpoch validOffsetAndEpoch = log.validateOffsetAndEpoch(fetchOffset, lastFetchedEpoch);
+
+            Optional<OffsetAndEpoch> latestSnapshotId = log.latestSnapshotId();
+            final ValidOffsetAndEpoch validOffsetAndEpoch;
+            if (fetchOffset == 0 && latestSnapshotId.isPresent()) {

Review Comment:
   I have tried to figure out some other cases we prefer to read the snapshot, a common case is `highWatermark` - `fetchOffset` > count(snapshot record). Do you think it's possible to write count(snapshot record) in the snapshot header?



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