From: Rick James Date: April 2 2012 9:44pm Subject: Re: Seconds Behind Master increasing in slave List-Archive: http://lists.mysql.com/replication/2321 Message-Id: <4F7A1DD2.1010809@yahoo-inc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit * 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 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