Comments on: Getting use of Slave in MySQL Replication http://www.mysqlperformanceblog.com/2007/02/14/getting-use-of-slave-in-mysql-replication/ Everything about MySQL Performance Wed, 19 Nov 2008 23:41:27 +0000 http://wordpress.org/?v=2.5.1 By: hosting http://www.mysqlperformanceblog.com/2007/02/14/getting-use-of-slave-in-mysql-replication/#comment-358507 hosting Mon, 29 Sep 2008 01:08:10 +0000 http://www.mysqlperformanceblog.com/2007/02/14/getting-use-of-slave-in-mysql-replication/#comment-358507 hosting thank you very much hosting thank you very much

]]> By: sohbet http://www.mysqlperformanceblog.com/2007/02/14/getting-use-of-slave-in-mysql-replication/#comment-355618 sohbet Tue, 16 Sep 2008 21:16:28 +0000 http://www.mysqlperformanceblog.com/2007/02/14/getting-use-of-slave-in-mysql-replication/#comment-355618 This can be very useful if you divide the tables in a database to difference slaves. Using the slave as much as possible greatly increases the chance most data is in cached in memory whereas the same query could be really, really slow on the master because it might not have much of it in cache This can be very useful if you divide the tables in a database to difference slaves. Using the slave as much as possible greatly increases the chance most data is in cached in memory whereas the same query could be really, really slow on the master because it might not have much of it in cache

]]> By: peter http://www.mysqlperformanceblog.com/2007/02/14/getting-use-of-slave-in-mysql-replication/#comment-138409 peter Fri, 22 Jun 2007 19:14:49 +0000 http://www.mysqlperformanceblog.com/2007/02/14/getting-use-of-slave-in-mysql-replication/#comment-138409 Not yet to be honest. I did not try 5.1 -> 5.0 Generally to be safe you better have Slaves at same or higher revision than the master. Not yet to be honest. I did not try 5.1 -> 5.0 Generally to be safe you better have Slaves at same or higher revision than the master.

]]> By: Jojo http://www.mysqlperformanceblog.com/2007/02/14/getting-use-of-slave-in-mysql-replication/#comment-138210 Jojo Fri, 22 Jun 2007 04:03:29 +0000 http://www.mysqlperformanceblog.com/2007/02/14/getting-use-of-slave-in-mysql-replication/#comment-138210 Quick question. Have you tried replicating from 5.1 (master) to 5.0.xx (slave)? I'm planning to do a downgrade of our existing db due to some problems I'm experiencing on 5.1. I'm planning to create a replica first then cutover to the replicas so as to minimize downtime. Looking forward to your reply. Thanks. Quick question. Have you tried replicating from 5.1 (master) to 5.0.xx (slave)? I’m planning to do a downgrade of our existing db due to some problems I’m experiencing on 5.1. I’m planning to create a replica first then cutover to the replicas so as to minimize downtime.

Looking forward to your reply. Thanks.

]]> By: Dmitry http://www.mysqlperformanceblog.com/2007/02/14/getting-use-of-slave-in-mysql-replication/#comment-135210 Dmitry Thu, 14 Jun 2007 15:13:19 +0000 http://www.mysqlperformanceblog.com/2007/02/14/getting-use-of-slave-in-mysql-replication/#comment-135210 That delay become random and once per 2-3 days, now we researching about. Thankx. That delay become random and once per 2-3 days, now we researching about.

Thankx.

]]> By: peter http://www.mysqlperformanceblog.com/2007/02/14/getting-use-of-slave-in-mysql-replication/#comment-135205 peter Thu, 14 Jun 2007 15:00:36 +0000 http://www.mysqlperformanceblog.com/2007/02/14/getting-use-of-slave-in-mysql-replication/#comment-135205 Dmitry, If replication is that delayed you need to tune it first as semi synchronous replication will cral very slow in such case. Dmitry,

If replication is that delayed you need to tune it first as semi synchronous replication will cral very slow in such case.

]]> By: Dmitry http://www.mysqlperformanceblog.com/2007/02/14/getting-use-of-slave-in-mysql-replication/#comment-135197 Dmitry Thu, 14 Jun 2007 14:39:47 +0000 http://www.mysqlperformanceblog.com/2007/02/14/getting-use-of-slave-in-mysql-replication/#comment-135197 Thanks, Peter. Will test it, cause delays sometimes 5 seconds before in slave appears this row. Thanks, Peter. Will test it, cause delays sometimes 5 seconds before in slave appears this row.

]]> By: peter http://www.mysqlperformanceblog.com/2007/02/14/getting-use-of-slave-in-mysql-replication/#comment-135182 peter Thu, 14 Jun 2007 13:38:10 +0000 http://www.mysqlperformanceblog.com/2007/02/14/getting-use-of-slave-in-mysql-replication/#comment-135182 Dmitry, Check Google Semi-Synchronous replication patches. Dmitry,

Check Google Semi-Synchronous replication patches.

]]> By: Dmitry http://www.mysqlperformanceblog.com/2007/02/14/getting-use-of-slave-in-mysql-replication/#comment-134974 Dmitry Wed, 13 Jun 2007 21:22:05 +0000 http://www.mysqlperformanceblog.com/2007/02/14/getting-use-of-slave-in-mysql-replication/#comment-134974 Exists any ways to create synced replication without delays or lags with mysql ? Exists any ways to create synced replication without delays or lags with mysql ?

]]> By: peter http://www.mysqlperformanceblog.com/2007/02/14/getting-use-of-slave-in-mysql-replication/#comment-53354 peter Sat, 17 Feb 2007 08:44:02 +0000 http://www.mysqlperformanceblog.com/2007/02/14/getting-use-of-slave-in-mysql-replication/#comment-53354 James there are many different circumstances out where. You may have just one slave in which case it might not overload master too badly. There are also different cases about reading stale data - in some cases you can use it if you have no choice in others it is absolutely critical data is reasonably recent. The thing is even non-critical queries might allow only certain delay - can you really use the slave if it is lagging by a week ? (And I've seen even worse cases). Designing how slaves are usage you should of course take your normal lag spikes in account - if you have nightly job which does 10min update queries - this will be normal lag time for you which does not cause switching. Regarding Alter Table - if it is long, in most cases the good idea is to run it on the slaves separately from the master and exclude it from replication. James there are many different circumstances out where. You may have just one slave in which case it might not overload master too badly. There are also different cases about reading stale data - in some cases you can use it if you have no choice in others it is absolutely critical data is reasonably recent.

The thing is even non-critical queries might allow only certain delay - can you really use the slave if it is lagging by a week ? (And I’ve seen even worse cases).

Designing how slaves are usage you should of course take your normal lag spikes in account - if you have nightly job which does 10min update queries - this will be normal lag time for you which does not cause switching.

Regarding Alter Table - if it is long, in most cases the good idea is to run it on the slaves separately from the master and exclude it from replication.

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