From: | Joshua Tolley <eggyknap(at)gmail(dot)com> |
---|---|
To: | "Birchall, Austen" <austen(dot)birchall(at)metoffice(dot)gov(dot)uk> |
Cc: | pgsql-novice(at)postgresql(dot)org |
Subject: | Re: More WAL archiving/backup questions |
Date: | 2011-05-14 13:44:04 |
Message-ID: | 4dce872b.c729440a.7a31.ffffd94b@mx.google.com |
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Lists: | pgsql-novice |
On Thu, May 12, 2011 at 02:29:41PM +0100, Birchall, Austen wrote:
> Hi once again
>
> Am I right to assume that running a pg_dumo -Fc against a database:
>
> (i) Does not require WAL log archiving be be switched on?
Correct.
> (ii) That running this will have no (or a very small) effect on the
> database's performance?
Not necessarily. pg_dump reads through all the data in every table, which can
certainly be a non-trivial IO load. Often people will direct pg_dump's output
to a file on the same filesystem as the database, which can certainly
overwhelm the disk. Sufficiently busy databases need to be careful about when
they backup.
> Also in general, are there any performance hits from runing in WAL
> Archiving mode and also any when a pg_start_backup is actually running
archive_mode being on or off probably doesn't make loads of performance
difference. pg_start_backup() causes a checkpoint, which can be IO intensive.
--
Joshua Tolley / eggyknap
End Point Corporation
http://www.endpoint.com
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