Re: Slow BLOBs restoring

From: Vlad Arkhipov <arhipov(at)dc(dot)baikal(dot)ru>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Slow BLOBs restoring
Date: 2010-12-09 03:58:08
Message-ID: 4D0053D0.4090200@dc.baikal.ru
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08.12.2010 22:46, Tom Lane writes:
> Are you by any chance restoring from an 8.3 or older pg_dump file made
> on Windows? If so, it's a known issue.
>
No, I tried Linux only.

> Not without a complete reproducible example ... and not at all if it's
> the known problem. The fix for that is to update pg_dump to 8.4 or
> later.
>
I think you can reproduce it. First I created a database full of many
BLOBs on Postres 8.4.5. Then I created a dump:

pg_dump -F c test > test.backup8

It took about 15 minutes. Then I tried to restore it on Postgres 8.

pg_restore -v -d test2 -j 2 test.backup8

It restored in 18 minutes. Then I restored it to Postgres 9.0.1, it took
20 minutes. Then I created a dump there:

/usr/pgsql-9.0/bin/pg_dump -F c test > test.backup9

It took 25 minutes. Finally I tried to restore it and got what I've
already described:

/usr/pgsql-9.0/bin/pg_restore -v -d test2 -j 2 test.backup9

However if I remove the option '-j', the database restores in 45 minutes.

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