From: Rick James
Date: July 26 2012 5:21pm
Subject: RE: How often the slave to pull data from master?
List-Archive: http://lists.mysql.com/mysql/227898
Message-Id: <2E7DD7ADE53B044C8C8BCD9C5829E1EB1489DB98C3@SP2-EX07VS01.ds.corp.yahoo.com>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable

My understanding is...

* There is a "permanent" connection (TCP/IP socket) between the Master and =
each Slave.  This is opened by the Slave when the slave starts (or restarts=
 or recovers from a network glitch).

* Master writes to binlog _and_ to that connection whenever there is a 'wri=
te' operation.  (I do not know whether the binlog is written/flushed before=
 or after or simultaneous with writing to the Slave(s).)

* If the connection is interrupted, the Slave will reconnect and ask the Ma=
ster for "old" info.  This comes from the binlog.  Otherwise, the Master's =
binlog file is not part of the flow of data from Master to Slave.

* Semi-sync (5.5) adds some chatter from Slave to Master so that the Master=
 can wait for at least one Slave to have written to its relay log.

* Percona Cluster, Galera, etc., add more complexity to the replication tra=
ffic.

> -----Original Message-----
> From: Keith Murphy [mailto:bmurphy@stripped]
> Sent: Thursday, July 26, 2012 9:45 AM
> To: Zhigang Zhang
> Cc: mysql@stripped
> Subject: Re: How often the slave to pull data from master?
>=20
> Yes, the slave pulls from the master. The slave io thread reads the
> information effectively as soon as it is written to the master's binary
> log.
>=20
> Keith
> On Jul 26, 2012 4:17 AM, "Zhigang Zhang" <zzgang2008@stripped> wrote:
>=20
> > Hello:
> >
> >
> >
> > I haven't read the source code of mysql ,but as I know ,the slave get
> > data from master server, rather than the master push data to slave.
> >
> >
> >
> > I think there is a timer to do this.
> >
> >
> >
> > Who can tell me the interval about the replication----how often the
> > slave to pull data from master?
> >
> >
> >
> > Thanks!
> >
> >
> >
> > Zhigang Zhang
> >
> >