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Re: Pg_upgrade speed for many tables

From: Magnus Hagander <magnus(at)hagander(dot)net>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Bruce Momjian <bruce(at)momjian(dot)us>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Pg_upgrade speed for many tables
Date: 2012-11-05 20:23:04
Message-ID: CABUevEzyaL2iiJqqa4BQHYbiScN3+H7JA_mduQm+mbMSYAXOqA@mail.gmail.com (view raw or flat)
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On Mon, Nov 5, 2012 at 9:14 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Bruce Momjian <bruce(at)momjian(dot)us> writes:
> > Magnus reported that a customer with a million tables was finding
> > pg_upgrade slow.
>
> You sure there's not an O(N^2) issue in there somewhere?


> > I don't see anything unsafe about having pg_upgrade use
> > synchronous_commit=off.
>
> No objection, but this seems unlikely to be better than linear speedup,
> with a not-terribly-large constant factor.
>
> BTW, does pg_upgrade run pg_restore in --single-transaction mode?
> That would probably make synchronous_commit moot, at least for that
> step.
>


It doesn't use pg_restore at all - it uses the dump from pg_dumpall, which
you can't reload with pg_restore.


-- 
 Magnus Hagander
 Me: http://www.hagander.net/
 Work: http://www.redpill-linpro.com/

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