From: Michael Paquier <michael.paquier@gmail.com>
To: Claudio Freire <klaussfreire@gmail.com>
Cc: Rambabu V <ram.wissen@gmail.com>
Cc: postgres performance list <pgsql-performance@postgresql.org>
Subject: Re: Need Help on wal_compression
Date: Wed, 10 Jan 2018 10:24:10 +0900
Message-ID: <20180110012410.GD336@paquier.xyz> (raw)
In-Reply-To: <CAGTBQpZcbQjj-wHjgUCGOTSC5jhY+aOMa-Eom-31jNt4GJcADg@mail.gmail.com>
References: <CADtiZxp0ksqNsM=uomMehcZafxWP+nvTyCCbT4Ejy9A_6GD6Fg@mail.gmail.com>
<CAGTBQpZcbQjj-wHjgUCGOTSC5jhY+aOMa-Eom-31jNt4GJcADg@mail.gmail.com>
On Tue, Jan 09, 2018 at 01:53:14PM -0300, Claudio Freire wrote:
> That shows 50% of that are full page writes. This is with compression
> enabled. WAL compression will only help FPW, so if you don't have a large
> volume of FPW, or they don't compress well, you won't benefit much.
This highly depends on the data types used as well. You won't get much
compressibility with things like UUIDs for example. When we worked on
the patch, I recall that FDW compression saved 25% for a relation with a
one-column integer, and only 12~15% when using UUIDs.
--
Michael
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To: pgsql-performance@postgresql.org
Cc: michael.paquier@gmail.com, klaussfreire@gmail.com, ram.wissen@gmail.com
Subject: Re: Need Help on wal_compression
In-Reply-To: <20180110012410.GD336@paquier.xyz>
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