I want to do do a tpcc benchark on a replicated database with a relatively large number of
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 milliseconds.
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.
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
> It all depends on your workload, though.
> 2010/1/27 Miguel Araújo <noradone@stripped>
> 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.
> Miguel Araújo
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