Sorry for the top post, just saying thanks, that's what I thought....
Back to the drawing board...
Jeff
> -----Original Message-----
> From: David Griffiths [mailto:dgriffiths@stripped]
> Sent: Wednesday, March 01, 2006 18:13
> To: mysql@stripped
> Cc: SGreen@stripped
> Subject: Re: Replication from multiple masters?
>
>
> Good point about the bin-logs. Yup - that would sink it. If
> mysql used individual binary logs per master database, it would work.
> Ya, if someone was silly enough to have two different
> databases with the same name, it would be bad, even with
> separate binary
> logs for each database.
>
> If you have two mysql instances on a single slave, you'll
> need more memory, faster CPUs, more disk space, etc. But it
> could be a
> viable option if the machine is just being used to provide a
> hot-standby.
>
>
> David
>
>
>
>
>
> SGreen@stripped wrote:
> >
> > MySQL cannot handle more than one incoming binlog at a time. The
> > facilities are just not in the code.
> >
> > You also run into a nightmare if a database exists on BOTH masters
> > (same
> > name on both systems) and the PK values of any tables (also with
> > matching names) overlap. If both masters update the
> "same" row at appx
> > the same time, we could run into deadlocking in the slave
> that didn't
> > happen on either master. It also means that the slave and
> at least one
> > of the masters will become out of sync (because the "other"
> master's
> > changes remain in the database) and replication is
> considered "broken"
> > at that point. It's a serious can of worms to handle multi-master
> > replication.
> >
> > Your two instances on one matching replicating to two
> separate masters
> > is not a multi-master replication (more than one master
> replicating with
> > a single slave) it's two single-master slave setups running
> on the same
> > machine. Close but not quite what the original post was
> looking for (I
> > don't think).
> >
> > Shawn Green
> > Database Administrator
> > Unimin Corporation - Spruce Pine
> >
> >
> >
> > David Griffiths <dgriffiths@stripped> wrote on 03/01/2006 04:34:26
> > PM:
> >
> > > That's not entirely true.
> > >
> > > You can have two instances of mysql running on the
> slave, and dbA
> > > connects to one instance, and dbB connects to the other. >
> > >
> > >
> > > Jeff, when you say, "different databases", do you mean that each
> > > master has a single mysql instance, and if you typed on M1,
> > >
> > > "show databases" you'd see (for example), "dbA"
> > >
> > > and if you did the same on M2, you'd see, "dbB"?
> > >
> > > If so, I wonder if there is another way to get around it:
> > >
> > > - create a virtual IP address that represents both
> masters. Use that
> > > virtual master in the my.cnf on the slave; each master has to
> > > have an identical replication account
> > >
> > > - put dbA and dbB on the slave
> > >
> > > - restrict replication from each master to their respective
> > > databases - "dbA" and "dbB" - ie don't replicate changes to the
> > > "mysql" database.
> > >
> > > The two masters appear as one (which overcomes the
> single-IP-address
> > > in the slave's my.cnf file), and each master has a different
> > > database inside the mysql instance, they aren't stepping on each
> > others toes.
> > >
> > > Just my 2 cents.
> > >
> > > David.
> > >
> > > Greg Donald wrote:
> > > > On 3/1/06, Jeff <jsmforum@stripped> wrote:
> > > >> Does anyone know if it's possible to replicate to a
> single slave from
> > > >> different databases on different masters?
> > > >>
> > > >> For instance:
> > > >>
> > > >> M1:dbA M2:dbB
> > > >> \ /
> > > >> rep rep
> > > >> \ /
> > > >> Slave
> > > >
> > > >
> > > >
> http://dev.mysql.com/doc/refman/5.1/en/replication-features.ht
ml
> > >
> > > <snip>MySQL only supports one master and many slaves.</snip>
> > >
> > >
> > >
> > > --
> > > Greg Donald
> > > Zend Certified Engineer
> > > MySQL Core Certification
> > > http://destiney.com/
> > >
> >
> > --
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> >
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