Re: Is WAL_DEBUG related code still relevant today?

On Wed, Dec 6, 2023, at 9:51 PM, Michael Paquier wrote:
> PerformWalRecovery() with its log for RM_XACT_ID is something that
> stresses me a bit though because this is in the main redo loop which
> is never free. The same can be said about GenericXLogFinish() because
> the extra computation happens while holding a buffer and marking it
> dirty. The ones in xlog.c are free of charge as they are called
> outside any critical portions.
>
> This makes me wonder how much we need to care about
> trace_recovery_messages, actually, and I've never used it.

IIUC trace_recovery_messages was a debugging aid in the 9.0 era when the HS was
introduced. I'm also wondering if anyone used it in the past years.

elog.c:

* Intention is to keep this for at least the whole of the 9.0 production
* release, so we can more easily diagnose production problems in the field.
* It should go away eventually, though, because it's an ugly and
* hard-to-explain kluge.
*/
int
trace_recovery(int trace_level)
{
if (trace_level < LOG &&
trace_level >= trace_recovery_messages)
return LOG;

return trace_level;
}

--
Euler Taveira
EDB https://www.enterprisedb.com/