September 3, 2014

Troubleshooting MySQL Upgrade Performance Regressions

So lets say you upgraded from MySQL 5.1 to Percona Server 5.5 and instead of expected performance improvement you see your performance being worse. What should you do ? First if you followed MySQL upgrade best practices such as testing your workload with pt-upgrade the chances of this happening are rather slim. But lets assume […]

Intel Nehalem vs AMD Opteron shootout in sysbench workload

Having two big boxes in our lab, one based Intel Nehalem (Cisco UCS C250) and second on AMD Opteron (Dell PowerEdge R815), I decided to run some simple sysbench benchmark to compare how both CPUs perform and what kind of scalability we can expect.

Data Corruption, DRBD and story of bug

Working with customer, I faced pretty nasty bug, which is actually not rare situation , but in this particular there are some lessons I would like to share. The case is pretty much described in bug 55981, or in pastebin. Everything below is related to InnoDB-plugin/XtraDB, but not to regular InnoDB ( i.e in MySQL […]

The story of one MySQL Upgrade

I recently worked on upgrading MySQL from one of very early MySQL 5.0 versions to Percona Server 5.1. This was a classical upgrade scenario which can cause surprises. Master and few slaves need to be upgraded. It is a shared database used by tons of applications written by many people over more than 5 years […]

mysql_upgrade and Innodb Tables

Upgrading from MySQL 5.0 to MySQL 5.1 or Percona Server 5.1 you may run into issues with mysql_upgrade – it will identify some tables to be upgraded and will attempt to run REPAIR TABLE for them. This will fail with “The storage engine for the table doesn’t support repair” error message. This seems to confuse […]

Rebuilding MySQL with same options

Every so often I am working on the system with custom compiled MySQL. How to upgrade to the new MySQL Options while preserving as much of original compilation options as possible if original build scripts are not available ? MySQL distribution has a great script called mysqlbug which was supposed to be used for bug […]

When is it a time to upgrade memory ?

Quite commonly I get a question similar to this – “My Innodb Buffer Pool is already 90% full, should I be thinking about upgrading memory already?” This is a wrong way to put the question. Unless you have very small database (read as database which is less than innodb_buffer_pool_size) You will have all buffer pool […]

What Bugs makes you to recomend upgrade most frequently ?

What bug makes you to recommend upgrading most frequently ? For me it is this bug which makes it quite painful to automate various replication tasks. It is not the most critical bug by far but this makes it worse – critical bugs would usually cause upgrades already or were worked around while such stuff […]

Economics of Performance Optimization

I think every person responsible for Development or Operations of growing application sooner or later have to decide on couple few questions on how to tackle application performance. These questions are: Should we Optimize Application or get more Hardware ? Should we do things ourselves or hire an experts to help us ? The answer […]

MySQL 4 to MySQL 5 Upgrade performance regressions

This week I already had two serious performance regression cases when upgrading from MySQL 4.0 and 4.1 to MySQL 5.0. By serious I mean several times performance difference not just 5-10% you often see for simple queries due to generally fatter code. The problem in both cases was MySQL 5.0 broken group commit bug. First […]