Re: pg_basebackup blocking all queries with horrible performance

From: Magnus Hagander <magnus(at)hagander(dot)net>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, Lonni J Friedman <netllama(at)gmail(dot)com>, Craig Ringer <ringerc(at)ringerc(dot)id(dot)au>, Jerry Sievers <gsievers19(at)comcast(dot)net>, pgsql-admin(at)postgresql(dot)org
Subject: Re: pg_basebackup blocking all queries with horrible performance
Date: 2012-06-10 10:43:32
Message-ID: CABUevEwYxpqA0EJ4pdcpLY6QZuK4DbmoRy_PC+NDCWKvCXwwkw@mail.gmail.com
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On Sat, Jun 9, 2012 at 2:51 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Fujii Masao <masao(dot)fujii(at)gmail(dot)com> writes:
>> This seems a bug. I think we should prevent pg_basebackup from
>> becoming synchronous standby. Thought?
>
> Absolutely.  If we have replication clients that are not actually
> capable of being standbys, there *must* be a way for the master
> to know that.

I thought we fixed this already by sending InvalidXlogRecPtr as flush
location? And that this only applied in 9.2?

Are you saying we picked pg_basebackup *in backup mode* (not log
streaming) as synchronous standby? If so then yes, that is
*definitely* a bug that should be fixed. We should never select a
connection that's not even streaming log as standby!

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

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