April 20, 2014

Troubleshooting MySQL Memory Usage

One of the most painful troubleshooting tasks with MySQL is troubleshooting memory usage. The problem usually starts like this – you have configured MySQL to use reasonable global buffers, such as innodb_buffer_size, key_buffer_size etc, you have reasonable amount of connections but yet MySQL takes much more memory than you would expect, causing swapping or other […]

How to Monitor MySQL with Percona’s Nagios Plugins

In this post, I’ll cover the new MySQL monitoring plugins we created for Nagios, and explain their features and intended purpose. I want to add a little context. What problem were we trying to solve with these plugins? Why yet another set of MySQL monitoring plugins? The typical problem with Nagios monitoring (and indeed with […]

Modeling MySQL Capacity by Measuring Resource Consumptions

There are many angles you can look at the system to predict in performance, the model baron has published for example is good for measuring scalability of the system as concurrency growths. In many cases however we’re facing a need to answer a question how much load a given system can handle when load is […]

Percona-XtraDB-9.1: released and new coming features

Recently Alexandr announced new Percona-XtraDB-9.1 release, and now it is good time to summarize features we have and what is expected soon. This release contains long waited features from 5.0: extended slow.log USER/TABLE/INDEX/CLIENT_STATISTICS + THREAD_STATISTICS ( coming in release-10) Extended slow.log is now even more extended, there is additional information for each query:

That […]

How Percona does a MySQL Performance Audit

Our customers or prospective customers often ask us how we do a performance audit (it’s our most popular service). I thought I should write a blog post that will both answer their question, so I can just reply “read all about it at this URL” and share our methodology with readers a little bit. This […]

Picking datatype for STATUS fields

Quite commonly in the applications you would need to use some kind of “status” field – status of order – “new”, “confirmed”, “in production”, “shipped” status of job, message etc. People use variety of ways to handle them often without giving enough thought to the choice which can cause problems later. Perhaps worst, though quite […]

Missing Data – rows used to generate result set

As Baron writes it is not the number of rows returned by the query but number of rows accessed by the query will most likely be defining query performance. Of course not all row accessed are created equal (such as full table scan row accesses may be much faster than random index lookups row accesses […]

Estimating Undo Space needed for LVM Snapshot

We know MySQL Backups using LVM are pretty cool (check out mylvmbackup) or MMM though it is quite typical LVM is not configurable properly to be usable for MySQL Backups. Quite frequently I find LVM installed on the system but no free space left to be used as snapshot undo space, which means LVM is […]

The MySQL optimizer, the OS cache, and sequential versus random I/O

In my post on estimating query completion time, I wrote about how I measured the performance on a join between a few tables in a typical star schema data warehousing scenario. In short, a query that could take several days to run with one join order takes an hour with another, and the optimizer chose […]

10+ Ways to Crash or Overload MySQL

People are sometimes contacting me and asking about bugs like this which provide a trivial way to crash MySQL to the user with basic privileges and asking me what to do. My answer to them is – there is nothing new to it and they just sit should back and relax Really – there are […]