Re: For what should pg_stop_backup wait?

From: Simon Riggs <simon(at)2ndquadrant(dot)com>
To: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: For what should pg_stop_backup wait?
Date: 2008-08-07 13:59:47
Message-ID: 1218117588.4549.497.camel@ebony.2ndQuadrant
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On Thu, 2008-08-07 at 21:11 +0900, Fujii Masao wrote:

> In HEAD, pg_stop_backup waits until the history file has been archived.
> But, in order to ensure that the last wal file was archived, pg_stop_backup
> should wait until not only the history file but also the backup stopping wal
> file has been archived, I think.
>
> Because the alphabetic order of the history file and the backup stopping
> wal file is not constant.

> If the backup starting wal file is the same as the stopping one (that is,
> any wal files were not switched during backup), the history file whose
> name consists of the starting one is behind the stopping one.
> Otherwise, the backup stopping wal file is behind the history file.

pg_stop_backup explicitly requests a log switch prior to writing the
history file, so this occurs in all cases. The assumption is wrong.

So yes, we should wait for stopxlogfilename, not histfilepath.

I'll do a patch. Thanks for your input.

--
Simon Riggs www.2ndQuadrant.com
PostgreSQL Training, Services and Support

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