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:[EMAIL PROTECTED] > Sent: Wednesday, March 01, 2006 18:13 > To: mysql@lists.mysql.com > Cc: [EMAIL PROTECTED] > 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 > > > > > > [EMAIL PROTECTED] 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 <[EMAIL PROTECTED]> 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 <[EMAIL PROTECTED]> 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/ > > > > > > > -- > > MySQL General Mailing List > > For list archives: http://lists.mysql.com/mysql > > To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED] > > -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED] -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
