| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Nathan Bossart <nathandbossart(at)gmail(dot)com>, Corey Huinker <corey(dot)huinker(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Jeff Davis <pgsql(at)j-davis(dot)com>, 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 19:52:22 |
| Message-ID: | zxpxlpaamrjdug6pk4z524ow7ddzvkoprrmx3yxprimvmuqdsa@tjsm77gfwr4l |
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| Lists: | pgsql-hackers |
Hi,
On 2025-03-06 14:47:08 -0500, Tom Lane wrote:
> Nathan Bossart <nathandbossart(at)gmail(dot)com> writes:
> > On Thu, Mar 06, 2025 at 01:47:34PM -0500, Tom Lane wrote:
> >> ... I wonder if we could just rip out pg_upgrade's support
> >> for DB-level parallelism, which is not terribly pretty anyway, and
> >> simply pass the -j switch straight to pg_dump and pg_restore.
>
> > That would certainly help for clusters with one big database with many LOs
> > or something, but I worry it would hurt the many database case quite a bit.
>
> I'm very skeptical of that. How many DBs do you know with just one table?
> I think most have enough that they could keep a reasonable number of
> CPUs busy with pg_dump's internal parallelism.
pg_dump as used by pg_upgrade doesn't need to dump table data. Afaict we only
do parallelism in pg_dump for table data and large objects. Outside of the
many-LOs case, there's nothing pg_dump's internal parallelism can accelerate?
So the number of tables in a database is irrelevant, no?
Greetings,
Andres Freund
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