Re: proposal - queryid can be used as filter for auto_explain

Hi

čt 18. 6. 2026 v 23:01 odesílatel Zsolt Parragi <zsolt.parragi@percona.com>
napsal:

> Hello
>
> +                                                          PGC_SUSET |
> GUC_LIST_INPUT,
> +                                                          0,
>
> Shouldn't that be PGC_SUSET, GUC_LIST_INPUT?
>

yes, fixed


>
> +       /*
> +        * In almost all cases, the queryid is computed due
> pg_stat_statements.
> +        * Without log_queryids computing queryid is not necessary, but it
> can
> +        * be hard to enable or disable queryid in dependecy of
> log_queryids.
> +        * There are two possibilities - force queryid computing, or ignore
> +        * queries without computed queryid (computing should be forced by
> setting
> +        * compute_query_id). Boths probably can work, first looks more
> clean
> +        * at this moment.
> +        */
> +       EnableQueryId();
>

I was not sure if we need to "force" queryid commuting, because usually it
will be computed due pg_stat_statements.
computing queryid is critical for pg_stat_statements, auto_explain can work
without it - only log_queryids will be ineffective.
But now I am sure, so EnableQueryId should be used in auto_explain too. For
consistency, for testing independence.
At the end - users can set compute_query_id to off.

I changed this comment to the same form as other usage of EnableQueryId.


> This comment seems misleading to me. Based on it, I would think that
> we always force queryid computing, but EnableQueryId doesn't do
> anything with compute_query_id = off, so it seems like the second
> choice instead? (also typo: Boths)
>
> +       result = (auto_explain_queryids *) guc_malloc(LOG, allocsize);
> +       if (result == NULL)
> +               return false;
>
> This leaks rawstring/elemlist, is that intentional?
>

Boths are allocated from shortlife memory context, and will be released
early. So there is no real risk of memory leaks.




>
> +       if (*newval == NULL || *newval[0] == '\0')
>
> That should be probably (*newval)[0].
>

I removed this - SplitGUCList can process empty strings. I leave this
routine, when I detect a zero element list.

Thank you for check and comments

Regards

Pavel