To recover a dropped or corrupt table with
href="https://launchpad.net/percona-data-recovery-tool-for-innodb" target="_new">Percona Data Recovery Tool for InnoDB you need two things: media with records(ibdata1, *.ibd, disk image, etc.) and a table structure. Indeed, there is no information about the table structure in an InnoDB page. Normally we either
href="http://www.mysqlperformanceblog.com/2008/12/17/recovering-create-table-statement-from-frm-file/" target="_new">recover the structure from .frm files or take it from some old backup.
To get a taste of the power of Tungsten Replicator, we will show how to switch roles. This is a controlled operation (as opposed to fail-over), where we can decide when to switch and which nodes are involved.
In our topology, host1 is the master, and we have three slaves. We can either ask for a switch and let the script select the first available slave, or tell the script which slave should be promoted. The script will show us the steps needed to perform the operation.
Tungsten Replicator is an open source tool that does high performance replication across database servers. It was designed to replace MySQL replication, although it also supports replication from and to Oracle and other systems. In this article, we will only cover MySQL replication, both simple and multi-master.
id="attachment_13396" class="wp-caption alignright" style="width: 257px">
class="size-full wp-image-13396" title="Percona Server for MySQL version 5.1.68-14.6" alt="Percona Server" src="http://www.mysqlperformanceblog.com/wp-content/uploads/2013/03/Percona-Server.jpg" width="247" height="97" />
class="wp-caption-text">Percona Server for MySQL version 5.1.68-14.6
MySQL 5.6.11 is here with many useful bug fixes. Not so good news - you won't be able to read about those bugs beyond the brief text in the release notes as many of the bug reports are behind the support paywall. If you have lots of time to spare maybe you can read diffs in the source tree on launchpad.
Swapping has always been something bad for MySQL performance but it is even more important for HA systems. It is so important to avoid swapping with HA that NDB cluster basically forbids calling malloc after the startup phase and hence its rather complex configuration.
Probably most readers of this blog know (or should know) about Linux swappiness setting, which basically controls how important is the file cache for Linux. Basically, with InnoDB, since the file cache is not important we add “vm.swappiness = 0″ to “/etc/sysctl.conf” and run “sysctl -p” and we are done.
Come see out new cool ‘cryogenic dolphin’ at the MySQL Community Reception Monday. Come hear about the latest 5.6 news from MySQL Engineers, see Cluster on Raspberry Pis, and walk away with our giveaways. And did I mention it is FREE?!?!
This blog post is part two of two. Like
href="http://www.mysqlperformanceblog.com/2013/04/16/is-your-mysql-buffer-pool-warm-make-it-sweat/" target="_blank">part one, published Wednesday, this is a cross-post from
href="https://engineering.groupon.com/2013/mysql/rotating-mysql-slow-logs-safely/" target="_blank">Groupon’s engineering blog. Thanks again to Kyle Oppenheim at Groupon. And one more reminder that I’ll be at the
Almost after every recovery case the same question arises. How many records were recovered and how many were lost.
Until now there were no means to answer the question without manual investigation. As it turned out a small change can make a big difference.
There are two ways to know how many records an InnoDB page stores. The index page has a header PAGE_N_RECS – this is a number of records the page stores. Obviously it doesn’t count any deleted records. The second method to know how many records are in the page is to follow by records pointers and just count them.