* 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
