On Thu, Aug 28, 2025 at 11:07 AM Ashutosh Sharma <ashu.coe...@gmail.com> wrote: > > We have seen cases where slot synchronization gets delayed, for example when > the slot is behind the failover standby or vice versa, and the slot sync > worker has to wait for one to catch up with the other. During this waiting > period, users querying pg_replication_slots can only see whether the slot has > been synchronized or not. If it has already synchronized, that’s fine, but if > synchronization is taking longer, users would naturally want to understand > the reason for the delay. > > Is there a way for end users to know the cause of slot synchronization > delays, so they can take appropriate actions to speed it up? > > I understand that server logs are emitted in such cases, but logs are not > something end users would want to check regularly. Moreover, since logging is > configuration-based, relevant messages may sometimes be skipped or suppressed. >
Currently, the way to see the reason for sync skip is LOGs but I think it is better to add a new column like sync_skip_reason in pg_replication_slots. This can show the reasons like standby_LSN_ahead_remote_LSN. I think ideally users can compare standby's slot LSN/XMIN with remote_slot being synced. Do you have any better ideas? -- With Regards, Amit Kapila.
