Re: pg_basebackup and wal streaming

From: Magnus Hagander <magnus(at)hagander(dot)net>
To: Yeb Havinga <yebhavinga(at)gmail(dot)com>
Cc: Dimitri Fontaine <dimitri(at)2ndquadrant(dot)fr>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: pg_basebackup and wal streaming
Date: 2011-08-16 14:51:33
Message-ID: CABUevEyAbT+sS_4j7dXeHndnDLZ5B1uTSDzDdAkeWzu2JmOygg@mail.gmail.com
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On Sat, Feb 26, 2011 at 20:59, Magnus Hagander <magnus(at)hagander(dot)net> wrote:
> On Sat, Feb 26, 2011 at 20:48, Yeb Havinga <yebhavinga(at)gmail(dot)com> wrote:
>> On 2011-02-26 18:19, Magnus Hagander wrote:
>>>
>>> Attached is an updated version of the patch that includes these
>>> changes, as well as Windows support and an initial cut at a ref page
>>> for pg_receivexlog (needs some more detail still).
>>
>> I'm testing a bit more (with the previous version, sorry) and got the
>> following while doing a stream backup from a cluster that was at that moment
>> doing a pgbench run with 1 synchronous standby.
>>
>> mgrid(at)mg79:~$ pg_basebackup --xlog=stream -D /data -vP -h mg73 -U repuser
>> Password:
>> xlog start point: 15/720000C8
>> pg_basebackup: starting background WAL receiver
>> pg_basebackup: got WAL data offset 14744, expected 16791960424        )
>> 5148915/5148026 kb g(100%) 1/1 tablespaces
>> xlog end point: 15/80568878
>> pg_basebackup: waiting for background process to finish streaming...
>> pg_basebackup: child process exited with error 1
>
> Hmm, strange. What platform are you on?
>
> I saw something similar *once* on Windows, but it then passed my tests
> a lot of times in a row so I figured it was just a "didn't clean
> properly" thing. Clearly there's a bug around.
>
> What's the size of the latest WAL file that it did work on? Is it
> 16791960424 bytes? That's way way to large, but perhaps it's not
> switching segment properly? (that value is supposedly the current
> write position in the file..)
>
>
>> I'm in total monkey test mode here, so I don't even know if I'm not supposed
>> to do the streaming variant while other stuff is going on.
>
> Oh yes, that's one of the main reasons to use it, so you should
> definitely be able to do that!
>

I've posted a new version of this patch at
http://archives.postgresql.org/pgsql-hackers/2011-08/msg00776.php -
forgot there was an open thread on this, sorry.

--
 Magnus Hagander
 Me: http://www.hagander.net/
 Work: http://www.redpill-linpro.com/

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