Dear Mikhail, Thanks for giving comments!
> But as far as I know, to solve this problem, we need to wait for slot.xmin > during the [0] > (WaitForOlderSnapshots) while creating index concurrently. WaitForOlderSnapshots() waits other transactions which can access older tuples than the specified (=current) transaction, right? I think it does not solve our issue. Assuming that same workloads [1] are executed, slot.xmin on node2 is arbitrary older than noted SQL, and WaitForOlderSnapshots(slot.xmin) is added in ReindexRelationConcurrently(). In this case, transaction older than slot.xmin does not exist at step 5, so the REINDEX will finish immediately. Then, the worker receives changes at step 7 so it is problematic if worker uses the reindexed index. From another point of view... this approach must fix REINDEX code, but we should not modify other component of codes as much as possible. This feature is related with the replication so that changes should be closed within the replication subdir. [1]: https://www.postgresql.org/message-id/TYAPR01MB5692541820BCC365C69442FFF54F2%40TYAPR01MB5692.jpnprd01.prod.outlook.com Best regards, Hayato Kuroda FUJITSU LIMITED
