From: Guillaume Lelarge <guillaume@lelarge.info>
To: Ivan Voras <ivoras@freebsd.org>
Cc: pgsql-performance@postgresql.org
Subject: Re: Backup strategies
Date: Wed, 15 Oct 2008 13:40:30 +0200
Message-ID: <48F5D6AE.3000601@lelarge.info> (raw)
In-Reply-To: <gd4gp6$f4p$1@ger.gmane.org>
References: <48F4D693.9000304@lerner.co.il>
<gd4d7q$3ed$1@ger.gmane.org>
<48F5BBFC.80404@krogh.cc>
<gd4gp6$f4p$1@ger.gmane.org>
Ivan Voras a écrit :
> Jesper Krogh wrote:
>>[...]
>> It worked when I tested it, but I may just have been darn lucky.
>
> No, it should be ok - I just didn't catch up with the times :) At least
> that's my interpretation of this paragraph in documentation:
>
> """Some backup tools that you might wish to use emit warnings or errors
> if the files they are trying to copy change while the copy proceeds.
> This situation is normal, and not an error, when taking a base backup of
> an active database; so you need to ensure that you can distinguish
> complaints of this sort from real errors..."""
>
> It looks like PostgreSQL freezes the state of the "data" directory in
> this case (and new data goes only to the transaction log - pg_xlog),
> which effectively creates an application-level snapshot. Good to know.
>
Nope. Even files in data directory change. That's why the documentation
warns against tools that emit errors for files that change during the copy.
--
Guillaume.
http://www.postgresqlfr.orghttp://dalibo.com
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To: pgsql-performance@postgresql.org
Cc: guillaume@lelarge.info, ivoras@freebsd.org
Subject: Re: Backup strategies
In-Reply-To: <48F5D6AE.3000601@lelarge.info>
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