Re: Synchronizing slots from primary to standby - Mailing list pgsql-hackers

On Thu, Feb 15, 2024 at 9:05 AM Zhijie Hou (Fujitsu)
<houzj.fnst@fujitsu.com> wrote:
>
> On Thursday, February 15, 2024 10:49 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > On Wed, Feb 14, 2024 at 7:26 PM Bertrand Drouvot
> >
> > Right, we can do that or probably this test would have made more sense with a
> > worker patch where we could wait for the slot to be synced.
> > Anyway, let's try to recreate the slot/subscription idea. BTW, do you think that
> > adding a LOG when we are not able to sync will help in debugging such
> > problems? I think eventually we can change it to DEBUG1 but for now, it can help
> > with stabilizing BF and or some other reported issues.
>
> Here is the patch that attempts the re-create sub idea.
>

Pushed this.

>
 I also think that a LOG/DEBUG
> would be useful for such analysis, so the 0002 is to add such a log.
>

I feel such a LOG would be useful.

+ ereport(LOG,
+ errmsg("waiting for remote slot \"%s\" LSN (%X/%X) and catalog xmin"
+    " (%u) to pass local slot LSN (%X/%X) and catalog xmin (%u)",

I think waiting is a bit misleading here, how about something like:
"could not sync slot information as remote slot precedes local slot:
remote slot \"%s\": LSN (%X/%X), catalog xmin (%u) local slot: LSN
(%X/%X), catalog xmin (%u)"

--
With Regards,
Amit Kapila.