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From:Revathi Rangachari Date:April 2 2012 11:51pm
Subject:Re: Seconds Behind Master increasing in slave
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Hi Rick

Both master and slave have same hardware configuration. The queries are not run parallel
in master/slave. I agree there is only one thread running on the slave for the updates.

Thanks
Revathi R
  
--- On Tue, 4/3/12, Rick James <rjames@stripped> wrote:

> From: Rick James <rjames@stripped>
> Subject: Re: Seconds Behind Master increasing in slave
> To: replication@stripped
> Date: Tuesday, April 3, 2012, 3:14 AM
> * If the Slave is less powerful than
> the Master (eg no RAID vs RAID), 
> hardware can contribute to the long delays.
> * If the queries on the Master are done in
> parallel,...  Replication 
> serializes the queries, thereby taking more elapsed time on
> the Slave.  
> (Note:  There is only one Update running on the slave,
> no matter how 
> many are queued up.)
> 
> On 4/2/12 1:58 PM, Arthur Fuller wrote:
> > The immediate  suspect is that single update
> statement. Is it a massive
> > batch-update? If so, is it possible to break it down
> into several smaller
> > updates, run successively?
> >
> > Arthur
> >
> > On Mon, Apr 2, 2012 at 4:26 PM, David
Lerer<DLerer@stripped> 
> wrote:
> >
> >> How long did the one update statement run?
> >> (A slow update, even if it is a single transaction,
> can slow down
> >> replication.
> >> David.
> >>
> >> -----Original Message-----
> >> From: Revathi Rangachari [mailto:masrrev@stripped]
> >> Sent: Monday, April 02, 2012 3:42 PM
> >> To: replication@stripped
> >> Subject: Seconds Behind Master increasing in slave
> >>
> >> Hi
> >>
> >> We have a master-slave setup.  The slave acts
> only as a replicate and does
> >> not cater to any client requests.
> >>
> >> Over the last 24 hours there has been more than 4
> to 6 hours delay in the
> >> replication.  The CPU, IO, memory usage all
> seem to be under control.  I
> >> changed the  SET GLOBAL
> innodb_flush_log_at_trx_commit = 0 ;
> >>
> >> The slave sql and io threads are running.
> >> show processlist shows only one update statement on
> a table.
> >>
> >> In spite of all this the slave still lags behind in
> replication by 5 hours.
> >>
> >> Any suggestion to improve the replication
> performance is highly
> >> appreciated.
> >>
> >> Thanks
> >> Revathi R
> >>
> >>
> 
> -- 
> Rick James - MySQL Geek
> 
> 
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Thread
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    • Re: adding another slavenhadie ramos1 Apr
      • Seconds Behind Master increasing in slaveRevathi Rangachari2 Apr
        • RE: Seconds Behind Master increasing in slaveDavid Lerer2 Apr
          • Re: Seconds Behind Master increasing in slaveArthur Fuller2 Apr
            • Re: Seconds Behind Master increasing in slaveRick James2 Apr
              • Re: Seconds Behind Master increasing in slaveRevathi Rangachari2 Apr
                • Re: Seconds Behind Master increasing in slavePankaj Joshi3 Apr
            • Re: Seconds Behind Master increasing in slaveRevathi Rangachari2 Apr
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                • Re: Seconds Behind Master increasing in slaveRevathi Rangachari2 Apr
          • RE: Seconds Behind Master increasing in slaveRevathi Rangachari2 Apr