| From: | Nathan Bossart <nathandbossart(at)gmail(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Corey Huinker <corey(dot)huinker(at)gmail(dot)com>, Jeff Davis <pgsql(at)j-davis(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Michael Paquier <michael(at)paquier(dot)xyz>, jian he <jian(dot)universality(at)gmail(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com>, Magnus Hagander <magnus(at)hagander(dot)net>, Stephen Frost <sfrost(at)snowman(dot)net>, Ashutosh Bapat <ashutosh(dot)bapat(dot)oss(at)gmail(dot)com>, Peter Smith <smithpb2250(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, alvherre(at)alvh(dot)no-ip(dot)org |
| Subject: | Re: Statistics Import and Export |
| Date: | 2025-03-06 01:36:29 |
| Message-ID: | Z8j8HXlIIGYPA9L8@nathan |
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| Lists: | pgsql-hackers |
On Wed, Mar 05, 2025 at 08:17:53PM -0500, Andres Freund wrote:
> Right now --statistics more than doubles the number of queries that pg_dump
> issues. That's oviously noticeable locally, but it's going to be really
> noticeable when dumping across the network.
>
> I think we need to do more to lessen the impact. Even leaving regression test
> performance aside, the time increase for the default pg_dump invocation will
> be painful for folks, particularly due to this being enabled by default.
>
> One fairly easy win would be to stop issuing getAttributeStats() for
> non-expression indexes. In most cases that'll already drastically cut down on
> the extra queries.
Apologies if this has already been considered upthread, but would it be
possible to use one query to gather all the required information into a
sorted table? At a glance, it looks to me like it might be feasible. I
had a lot of luck with reducing the number per-object queries with that
approach recently (e.g., commit 2329cad).
--
nathan
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