Message-ID: <496F2795.70105@enterprisedb.com>
Date: Thu, 15 Jan 2009 14:09:57 +0200
Organization: EnterpriseDB
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To: Bruce Momjian <bruce@momjian.us>
CC: Fujii Masao <masao.fujii@gmail.com>, Randy Isbell <jisbell@cisco.com>,
	pgsql-bugs@postgresql.org
Subject: Re: BUG #4566: pg_stop_backup() reports incorrect STOP WAL
 LOCATION
References: <200901150150.n0F1oV113850@momjian.us>
In-Reply-To: <200901150150.n0F1oV113850@momjian.us>
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From: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>

I think not 
(http://archives.postgresql.org/pgsql-hackers/2008-12/msg00126.php). The 
return value of pg_stop_backup() is currently the same as 
pg_switch_xlog()'s: the location of the last byte before the XLOG switch 
+ 1. The proposed patch would remove the "+ 1". Seems like an 
unnecessary API change, and I don't recall any reason why the new 
definition would be better.

A fix for the broken waiting behavior discussed in that thread was 
committed.

Bruce Momjian wrote:
> Would someone please tell me if this should be applied?
> 
> ---------------------------------------------------------------------------
> 
> Fujii Masao wrote:
>> 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
> 
> [ Attachment, skipping... ]
> 
>> -- 
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> 


-- 
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com