November 1, 2014

Sharing an auto_increment value across multiple MySQL tables (revisited)

A couple of weeks ago I blogged about Sharing an auto_increment value across multiple MySQL tables. In the comments, a few people wrote in to suggest alternative ways of implementing this.  I just got around to benchmarking those alternatives today across two large EC2 machines:

Sharing an auto_increment value across multiple MySQL tables

The title is SEO bait – you can’t do it. We’ve seen a few recurring patterns trying to achieve similar – and I thought I would share with you my favorite two: Option #1: Use a table to insert into, and grab the insert_id:

Option #2: Use a table with one just row:

mysqld_multi: How to run multiple instances of MySQL

The need to have multiple instances of MySQL (the well-known mysqld process) running in the same server concurrently in a transparent way, instead of having them executed in separate containers/virtual machines, is not very common. Yet from time to time the Percona Support team receives a request from a customer to assist in the configuration of […]

A closer look at the MySQL ibdata1 disk space issue and big tables

A recurring and very common customer issue seen here at the Percona Support team involves how to make the ibdata1 file “shrink” within MySQL. I can only imagine there’s a degree of regret by some of the InnoDB architects on their design decisions regarding disk-space management by the shared tablespace* because this has been a big […]

Generating test data for MySQL tables

One of the common tasks requested by our support customers is to optimize slow queries. We normally ask for the table structure(s), the problematic query and sample data to be able to reproduce the problem and resolve it by modifying the query, table structure, or global/session variables. Sometimes, we are given access to the server […]

The use of Iptables ClusterIP target as a load balancer for PXC, PRM, MHA and NDB

Most technologies achieving high-availability for MySQL need a load-balancer to spread the client connections to a valid database host, even the Tungsten special connector can be seen as a sophisticated load-balancer. People often use hardware load balancer or software solution like haproxy. In both cases, in order to avoid having a single point of failure, […]

Multiple column index vs multiple indexes with MySQL 5.6

A question often comes when talking about indexing: should we use multiple column indexes or multiple indexes on single columns? Peter Zaitsev wrote about it back in 2008 and the conclusion then was that a multiple column index is most often the best solution. But with all the recent optimizer improvements, is there anything different with […]

Sysbench with support of multi-tables workload

We just pushed to sysbench support for workload against multiple tables ( traditionally it used only single table). It is available from launchpad source tree lp:sysbench . This is set of LUA scripts for sysbench 0.5 ( it supports scripting), and it works following way: – you should use –test=tests/db/oltp.lua to run OLTP test i.e. […]

Spreading .ibd files across multiple disks; the optimization that isn’t

Inspired by Baron’s earlier post, here is one I hear quite frequently – “If you enable innodb_file_per_table, each table is it’s own .ibd file.  You can then relocate the heavy hit tables to a different location and create symlinks to the original location.” There are a few things wrong with this advice:

The Doom of Multiple Storage Engines

One of the big “Selling Points” of MySQL is support for Multiple Storage engines, and from the glance view it is indeed great to provide users with same top level SQL interface allowing them to store their data many different way. As nice as it sounds the in theory this benefit comes at very significant […]