Message-ID: <503C6B02.5070104@ringerc.id.au>
Date: Tue, 28 Aug 2012 14:53:54 +0800
From: Craig Ringer <ringerc@ringerc.id.au>
User-Agent: Mozilla/5.0 (X11; Linux x86_64;
	rv:14.0) Gecko/20120717 Thunderbird/14.0
MIME-Version: 1.0
To: Nimesh Satam <nimesh.zedo@gmail.com>
CC: pgsql-performance@postgresql.org
Subject: Re: Vacuum problems with 9.1
References: 
 <CACemtiN4fMC1Xgbuh=Tdr7fWP_4GqLgYnd=nacz9xHbH7VDFMQ@mail.gmail.com>
In-Reply-To: 
 <CACemtiN4fMC1Xgbuh=Tdr7fWP_4GqLgYnd=nacz9xHbH7VDFMQ@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit

On 08/28/2012 12:33 PM, Nimesh Satam wrote:
> Hi,
>
> We have been using the current version of postgres i.e. 9.1.4 with
> streaming replication on. While vacuuming we noticed that certain dead
> rows are not getting removed and following debug information is printed:
>
> "DETAIL: 12560 dead row versions cannot be removed yet."
>
> As per suggestion, we made sure that no long running transactions are
> active. Also all the applications were stopped during this time.
>
> Can anybody highlight the possible reason for the dead rows not been
> cleaned?

I don't know if prepared transactions could cause this exact message, 
but check:

     select * from pg_prepared_xacts ;

to see if you have any prepared transactions (from two-phase commit) 
lying around.

If you don't use XA or 2PC, consider setting  max_prepared_transactions 
to 0 in postgresql.conf if it isn't already.

--
Craig Ringer