From: henk de wit <henk53602@hotmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-performance@postgresql.org
Subject: Re: How to get parallel restore in PG 8.4 to work?
Date: Thu, 2 Apr 2009 22:18:20 +0200
Message-ID: <COL104-W101E9D4DF3EB37242C9926F5880@phx.gbl> (raw)
In-Reply-To: <4107.1238593597@sss.pgh.pa.us>
References: <COL104-W6288B22DCD85FC12769A2F58A0@phx.gbl>
<20300.1238540913@sss.pgh.pa.us>
<COL104-W61EE9F7AF2E58BCC54F122F58B0@phx.gbl>
<4107.1238593597@sss.pgh.pa.us>
>> I still have some work to do to find out why dumping in the custom
>> format is so much slower.
>
> Offhand the only reason I can see for it to be much different from
> plain-text output is that -Fc compresses by default. If you don't
> care about that, try -Fc -Z0.
Ok, I did some performance testing today and I appeared to be wrong after all. My apologies for the noise.
Here are some test results:
Scenarioxfsjfs patchedjfscat backup | gunzip | psql45 min--pg_dump> hdd (uncompressed) (==pg_dump -Fp)--10 min 15 secpg_dump -Fc> hdd (uncompressed)10 min 20 sec10 min 21 sec10 min 28 secpg_dump -Fc | gzip> hdd11 min 20 sec11 min 25 sec12 min 04 secpg_restore 8 threads14 min 23 sec11 min 40 sec11 min 20 secpg_restore 16 threads11 min 46 sec12 min 40 sec12 min 33 secpg_restore 32 threads11 min 42 sec12 min 30 sec12 min 30 sec
As can be seen in the table (hope this renders correctly on the mailing list), there is barely a difference between a plain dump and a custom format dump. For who it concerns, xfs performance a little better than jfs here, but the difference is marginal. More on topic, beyond 16 processes there isn't any notable speed improvement for the parallel restore (as expected).
Kind regards,Henk
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To: pgsql-performance@postgresql.org
Cc: henk53602@hotmail.com, tgl@sss.pgh.pa.us
Subject: Re: How to get parallel restore in PG 8.4 to work?
In-Reply-To: <COL104-W101E9D4DF3EB37242C9926F5880@phx.gbl>
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