Remove assertion that circular buffer entries are monotonic

arssher · arssher · commit 81efb85f2676 · 2018-09-20T10:57:59.000+03:00
GetOldestXmin *can* go backwards, see its comment. For the record, spotted by shardman's test_worker_failover_with_offline_neighbour test: apparently LR launcher background worker gets low oldestxmin on its start because it is not connected to any database. (cherry picked from commit a3554d5)
diff --git a/src/backend/access/transam/global_snapshot.c b/src/backend/access/transam/global_snapshot.c
@@ -282,7 +282,6 @@ GlobalSnapshotMapXmin(GlobalCSN snapshot_global_csn)
 
 	Assert(TransactionIdIsNormal(current_oldest_xmin));
 	Assert(TransactionIdIsNormal(previous_oldest_xmin));
-	Assert(TransactionIdFollowsOrEquals(current_oldest_xmin, previous_oldest_xmin));
 
 	gap = csn_seconds - last_csn_seconds;
 	offset = csn_seconds % gsXidMap->size;
