From: Ron <ronljohnsonjr@gmail.com>
To: pgsql-admin@lists.postgresql.org
Subject: Re: too high planning time
Date: Thu, 2 Feb 2023 12:57:04 -0600
Message-ID: <f4680777-8023-6627-bd23-98563b6512e2@gmail.com> (raw)
In-Reply-To: <CAC0w7LKLV5XV=dW-9Y4g2Tezq+aBnSa5Gz6GKrHf_gdf1kG7Gg@mail.gmail.com>
References: <CAC0w7LKjDd16T80CYejmMrht1Ddjcf1P8jg1POdH=RyRxCHLXA@mail.gmail.com>
<1536295.1675351465@sss.pgh.pa.us>
<CAC0w7LKLV5XV=dW-9Y4g2Tezq+aBnSa5Gz6GKrHf_gdf1kG7Gg@mail.gmail.com>
pg_stat_activity is the place to look.
This tells you all of the blocked pids:
SELECT pid
, username
, pg_blocking_pids(pid) AS blocked_by
, left(query, 100) as blocked_query
FROM pg_stat_activity
WHERE CARDINALITY(blocking_pids(pid)) > 0;
From there, you can see what the blocking pid is doing.
On 2/2/23 12:21, Kenny Bachman wrote:
> In fact, when I run the query for the second time, it returns very fast
> results. But after a while the problem reoccurs.
> Not just for these queries, but almost all queries in the database are
> slowed down this way.
> Is it normal to have a lock on the catalog or system tables? What should I
> do when this happens on pg_statistic or other catalogs?
>
> thanks a lot for your comments and help
> Kenny
>
> Tom Lane <tgl@sss.pgh.pa.us>, 2 Şub 2023 Per, 18:24 tarihinde şunu yazdı:
>
> Kenny Bachman <kenny.bachman17@gmail.com> writes:
> > EXPLAIN ANALYZE select
> > i."DefinitionId",
> > from
> > "T_WF_INSTANCE" i
> > where
> > i."InstanceId" = 10045683193;
>
> > QUERY PLAN
>
> >
> --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> > Index Scan using
> > "T_WF_INSTANCE_InstanceId_ApplicationCd_EntityStatusCd_idx" on
> > "T_WF_INSTANCE" i (cost=0.57..2.79 rows=1 width=34) (actual
> > time=2.522..2.522 rows=1 loops=1)
> > Index Cond: ("InstanceId" = '10045683193'::bigint)
>
> > * Planning Time: 8460.446 ms Execution Time: 2.616 ms*
> > (4 rows)
>
> It's hard to believe that such a simple query could take that
> long to plan. What I'm wondering is if the planner got blocked
> on some other session's exclusive lock. Not a lock on
> "T_WF_INSTANCE" itself, because we'd have got that lock during
> parsing before the "Planning Time" measurement starts. But
> there's going to be a physical access to the table's index
> to determine its tree height, so an ex-lock on the index could
> explain this. Or an ex-lock on catalogs, particularly pg_statistic.
> What else is going on in your database when this happens?
>
> regards, tom lane
>
--
Born in Arizona, moved to Babylonia.
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To: pgsql-admin@postgresql.org
Cc: ronljohnsonjr@gmail.com, pgsql-admin@lists.postgresql.org
Subject: Re: too high planning time
In-Reply-To: <f4680777-8023-6627-bd23-98563b6512e2@gmail.com>
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