Re: Change log level for notifying hot standby is waiting non-overflowed snapshot

On 2025/02/03 22:35, torikoshia wrote:
> Hi,
>
> When a hot standby is restarted in a state where subtransactions have overflowed, it may become inaccessible:
>
>   $ psql: error: connection to server at "localhost" (::1), port 5433 failed: FATAL:  the database system is not yet accepting connections
>           DETAIL:  Consistent recovery state has not been yet reached.

Could you share the steps to reproduce this situation?

> However, the log message that indicates the cause of this issue seems to be only output at the DEBUG1 level:
>
>   elog(DEBUG1,
>        "recovery snapshot waiting for non-overflowed snapshot or "
>        "until oldest active xid on standby is at least %u (now %u)",
>        standbySnapshotPendingXmin,
>        running->oldestRunningXid);
>
> I believe this message would be useful not only for developers but also for users.

Isn't this log message too difficult for most users? It seems to
describe PostgreSQL's internal mechanisms, making it hard
for users to understand the issue and what actions to take.

Regards,

--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION