Re: BUG #4566: pg_stop_backup() reports incorrect STOP WAL LOCATION

On Fri, Dec 5, 2008 at 11:41 PM, Randy Isbell <jisbell@cisco.com> wrote:
>
> The following bug has been logged online:
>
> Bug reference:      4566
> Logged by:          Randy Isbell
> Email address:      jisbell@cisco.com
> PostgreSQL version: 8.3.4
> Operating system:   FreeBSD 6.2
> Description:        pg_stop_backup() reports incorrect STOP WAL LOCATION
> Details:
>
> An inconsistency exists between the segment name reported by
> pg_stop_backup() and the actual WAL file name.
>
>
> SELECT pg_start_backup('filename');
>         pg_start_backup
>        -----------------
>         10/FE1E2BAC
>        (1 row)
>
> Later:
> SELECT pg_stop_backup();
>         pg_stop_backup
>        ----------------
>         10/FF000000
>        (1 row)
>
> The resulting *.backup file:
>
> START WAL LOCATION: 10/FE1E2BAC (file 0000000200000010000000FE)
> STOP WAL LOCATION: 10/FF000000 (file 0000000200000010000000FF)
> CHECKPOINT LOCATION: 10/FE1E2BAC
> START TIME: 2008-11-09 01:15:06 CST
> LABEL: /bck/db/sn200811090115.tar.gz
> STOP TIME: 2008-11-09 01:15:48 CST
>
> In my 8.3.4 instance, WAL file naming occurs as:
>
> ...
> 0000000100000003000000FD
> 0000000100000003000000FE
> 000000010000000400000000
> 000000010000000400000001
> ...
>
> WAL files never end in 'FF'.  This causes a problem when trying to collect
> the ending WAL file for backup.

It's a bug of pg_stop_backup(), which has been talked before.
http://archives.postgresql.org/pgsql-hackers/2008-12/msg00108.php

Attached is a patch against HEAD. I think that we should
also backport.

Regards,

--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center