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Re: Pg_upgrade speed for many tables

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Bruce Momjian <bruce(at)momjian(dot)us>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Magnus Hagander <magnus(at)hagander(dot)net>
Subject: Re: Pg_upgrade speed for many tables
Date: 2012-11-05 20:14:40
Message-ID: 23703.1352146480@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
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.

			regards, tom lane


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