From: Tom Lane <tgl@sss.pgh.pa.us>
To: Jerry Sievers <gsievers19@comcast.net>
cc: Bruce Momjian <bruce@momjian.us>, Kevin Grittner <kgrittn@ymail.com>,
 "pgsql-admin\@postgresql.org" <pgsql-admin@postgresql.org>
Subject: Re: Dump/Reload pg_statistic to cut time from pg_upgrade?
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 <87r4f65sdm.fsf@comcast.net>
Comments: In-reply-to Jerry Sievers <gsievers19@comcast.net>
 message dated "Wed, 10 Jul 2013 10:47:33 -0500"
Date: Wed, 10 Jul 2013 12:46:26 -0400
Message-ID: <26325.1373474786@sss.pgh.pa.us>
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Jerry Sievers <gsievers19@comcast.net> writes:
> Kevin Grittner <kgrittn@ymail.com> writes:
>> Jerry Sievers <gsievers19@comcast.net> wrote:
>>> Planning to pg_upgrade some large (3TB) clusters using hard link
>>> method.  Run time for the upgrade itself takes around 5 minutes.
>>> Unfortunately the post-upgrade analyze of the entire cluster is going
>>> to take a minimum of 1.5 hours running several threads to analyze all
>>> tables.  This was measured in an R&D environment.

At least for some combinations of source and destination server
versions, it seems like it ought to be possible for pg_upgrade to just
move the old cluster's pg_statistic tables over to the new, as though
they were user data.  pg_upgrade takes pains to preserve relation OIDs
and attnums, so the key values should be compatible.  Except in
releases where we've added physical columns to pg_statistic or made a
non-backward-compatible redefinition of statistics meanings, it seems
like this should Just Work.  In cases where it doesn't work, pg_dump
and reload of that table would not work either (even without the
anyarray problem).

			regards, tom lane


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