Miguel - It varies from machine to machine, network to network, depends on
several factors like load, the sql you tested and more over all hardware
components present in the server.
2010/1/27 Miguel Araújo <noradone@stripped>
> I want to do do a tpcc benchark on a replicated database with a relatively
> large number of replicas.
> The major timing issue is right what you've said "when an event will get
> *executed* on the slave", but I don't want to measure the occasional
> multisecond delay. As you said, replication is generally fast (in order of
> milliseconds), and my intention is to measure this delay in the order of
> So, my approach is to read (each 10ms) the binary logs on master and each
> slave as the benchmark runs, and compare the position to finally calculate
> the delay time. And, like I've started questioning in this thread, my doubt
> is on what relay log to read.
> Miguel Araújo.
> On Jan 27, 2010, at 2:35 PM, Johan De Meersman wrote:
> > The event *arrives* pretty soon after - unless you have a flaky network,
> that's not really you should worry about.
> > The major timing issue will be when an event will get *executed* on the
> slave, and the answer is: it varies. Events get executed sequentially on the
> slave, so although it will generally be fast (order of milliseconds), a huge
> update or other long-running query will block the queue until it finishes,
> and thus you could see the occasional multisecond delay.
> > It all depends on your workload, though.
> > 2010/1/27 Miguel Araújo <noradone@stripped>
> > Hello.
> > I want to measure replication speed for a great number of replicas. By
> that I mean how soon an event arrives at the slave after being logger to the
> master's binary log.
> > So, I've started developing an application to read the replication logs
> in order to compare them (compare by time, the log position on the master
> node with the log position on the slave's). My first approach was to use the
> mysqlbinlog to get the log position, in the 'Master_Log_File'. But in the
> slave's the last position that the SQL thread has read and executed is the
> 'Relay_Log_Pos', right?
> > I have to read the slave's relay log, in order to get the last position
> on the Master's log executed? And compare with the master's log?
> > Thank you.
> > Regards,
> > Miguel Araújo
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