Re: Problems around compute_query_id

Hi,

On Mon, Apr 12, 2021 at 02:56:59PM +0800, Julien Rouhaud wrote:
> On Mon, Apr 12, 2021 at 03:12:40PM +0900, Michael Paquier wrote:
> > Fujii-san has reported on Twitter that enabling the computation of
> > query IDs does not work properly with log_statement as the query ID is
> > calculated at parse analyze time and the query is logged before that.
> > As far as I can see, that's really a problem as any queries logged are
> > combined with a query ID of 0, and log parsers would not really be
> > able to use that, even if the information provided by for example
> > log_duration gives the computed query ID prevent in pg_stat_activity.
>
> I don't see any way around that. The goal of log_statements is to log all
> syntactically valid queries, including otherwise invalid queries. For
> instance, it would log
>
> SELECT notacolumn;
>
> and there's no way to compute a queryid in that case. I think that
> log_statements already causes some issues with log parsers. At least pgbadger
> recommends to avoid using that:
>
> "Do not enable log_statement as its log format will not be parsed by pgBadger."
>
> I think we should simply document that %Q is not compatible with
> log_statements.

What about log_statement_sample_rate ? Does compute_query_id have the
same problem with that?

Michael

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