|From:||Julien Rouhaud <rjuju123(at)gmail(dot)com>|
|To:||Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>|
|Cc:||robertmhaas(at)gmail(dot)com, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>|
|Subject:||pg_stat_statements issue with parallel maintenance (Was Re: WAL usage calculation patch)|
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On Sat, Mar 28, 2020 at 02:38:27PM +0100, Julien Rouhaud wrote:
> On Sat, Mar 28, 2020 at 04:14:04PM +0530, Amit Kapila wrote:
> > I see some basic problems with the patch. The way it tries to compute
> > WAL usage for parallel stuff doesn't seem right to me. Can you share
> > or point me to any test done where we have computed WAL for parallel
> > operations like Parallel Vacuum or Parallel Create Index?
> Ah, that's indeed a good point and AFAICT WAL records from parallel utility
> workers won't be accounted for. That being said, I think that an argument
> could be made that proper infrastructure should have been added in the original
> parallel utility patches, as pg_stat_statement is already broken wrt. buffer
> usage in parallel utility, unless I'm missing something.
Just to be sure I did a quick test with pg_stat_statements behavior using
parallel/non-parallel CREATE INDEX and VACUUM, and unsurprisingly buffer usage
doesn't reflect parallel workers' activity.
I added an open for that, and adding Robert in Cc as 9da0cc352 is the first
commit adding parallel maintenance.
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