Re: pg_dump incredibly slow dumping a single schema from a large db

From: Mike Roest <mike(dot)roest(at)replicon(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers(at)postgresql(dot)org, pgsql-general(at)postgresql(dot)org
Subject: Re: pg_dump incredibly slow dumping a single schema from a large db
Date: 2012-03-31 20:34:26
Message-ID: CAE7ByhhDgMdiALoGwpu+UXunP=iM9wJHWynfuk8bBhYNYH2bPQ@mail.gmail.com
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>
> I've committed fixes for both these issues. If you are in a position to
> test with 9.1 branch tip from git, it'd be nice to have confirmation
> that these patches actually cure your problem. For both of them, the
> issue seems to only show up in a subset of cases, which may explain why
> we'd not identified the problem before.
>
> regards, tom lane
>
Cool,
I've grabbed your changes and it seems to have completely cured the issue.

reading user-defined tables has gone down to 9 seconds from 2.5 minutes
reading dependency data has gone down to 20 seconds from 5.5 minutes.

Thanks so much Tom this is perfect. I'm just pulling another backup using
the stock 9.1.1 pg_dump to ensure the backups are equivalent.

Any idea when 9.1.4 with this change will be out so we can pull the cluster
up.

With regards to your previous question about sequences there are 61K in the
DB, looks like our schema currently has about 115 sequences per tenant.

--Mike

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