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Peter ZaitsevToday I’ve upgraded MySQL Server on the host running MySQL Performance Blog. MySQL 4.1.12 was running here for well over a year before that. Why Have not I upgraded before ? Well because it just worked fine. Yes I know there were some security fixes but I have dedicated server with remote MySQL access closed […]
I’m happy to announce availability of MySQL Performance Forums on MySQL Performance Blog. This forum is created as free alternative to MySQL Consulting Services which we provide. If you would like to get some free help to your performance issues please use forums so everyone else could benefit from our replies. You also should get […]
One little known fact about MySQL Indexing, however very important for successfull MySQL Performance Optimization is understanding when exactly MySQL is going to use index and how it is going to do them. So if you have table people with KEY(age,zip) and you will run query something like SELECT name FROM people WHERE age BETWEEN […]
Jay Pipes continues cache experiements and has compared performance of MySQL Query Cache and File Cache. Jay uses Apache Benchmark to compare full full stack, cached or not which is realistic but could draw missleading picture as contribution of different components may be different depending on your unique applications. For example for application containing a […]
Recently Jay Pipes published great article about lazy connecting and caching which reminded me my post on this matter is well overdue. Let me start with couple of comments about Jays article. First – caching in files should be used with caution. It may be very efficient especially if number of cached objects is small […]
Baron wrote a nice article comparing locking hints in MySQL and SQL Server. In MySQL/Innodb SELECT LOCK IN SHARE MODE and SELECT FOR UPDATE are more than hints. The behavior will be different from normal SELECT statements. Here is a simple example:
One of very interesting techniques Innodb uses is technique called “doublewrite” It means Innodb will write data twice when it performs table space writes – writes to log files are done only once. Why is Doublewrite is needed? It is needed to archive data safety in case of partial page writes. Innodb does not log […]
If you care about archiving best performance in your application using MySQL you should learn about prepared statements. These do not neccesary provide performance beneft but they may, they also have other benefits. As a quick introduction – before MySQL 4.1 there were only textual statements and textual protocol for data transfer – query was […]
I’m leaving MySQL starting 1st of August. This is surely not news for my collegues and friends who knew this is comming. We’re starting our own company which will provide MySQL Consulting services. We’ll focus on MySQL Performance Optimization but will be able to help pretty much with all MySQL related issues. We can also […]
MySQL is known for its stability but as any other application it has bugs so it may crash sometime. Also operation system may be flawed, hardware has problems or simply power can go down which all mean similar things – MySQL Shutdown is unexpected and there could be various inconsistences. And this is not only […]
MySQL has a great feature called “Query Cache” which is quite helpful for MySQL Performance optimization tasks but there are number of things you need to know. First let me clarify what MySQL Query Cache is – I’ve seen number of people being confused, thinking MySQL Query Cache is the same as Oracle Query Cache […]
One nice feature added for EXPLAIN statement in MySQL 4.1 is EXTENDED keyword which provides you with some helpful additional information on query optimization. It should be used together with SHOW WARNINGS to get information about how query looks after transformation as well as what other notes optimizer may wish to tell us. It is […]
Running EXPLAIN for problematic queries is very powerful tool for MySQL Performance optimization. If you’ve been using this tool a lot you probably noticed it is not always provide adequate information. Here is list of things you may wish to watch out. EXPLAIN can be wrong – this does not happen very often but it […]
Many people asked me to publish a walk through SHOW INNODB STATUS output, showing what you can learn from SHOW INNODB STATUS output and how to use this info to improve MySQL Performance. What is SHOW INNODB STATUS To start with basics, SHOW INNODB STATUS is a command which prints out a lot of internal […]
Have you seen recent eWeek benchmarks which test OpenSource stacks and compare them to .NET ? Here is what was compared and here are results. Results make me ask number of questions – why WAMP would perform 6 times better than LAMP ? Why Python would be faster than PHP on Windows but slower on […]
After playing yesterday a bit with INSERT … SELECT I decided to check is Innodb locks are relly as efficient in terms of low resource usage as they are advertised. Lets start with a bit of background – in Innodb row level locks are implemented by having special lock table, located in the buffer pool […]
Everyone using Innodb tables probably got use to the fact Innodb tables perform non locking reads, meaning unless you use some modifiers such as LOCK IN SHARE MODE or FOR UPDATE, SELECT statements will not lock any rows while running. This is generally correct, however there a notable exception – INSERT INTO table1 SELECT * […]
Brian Aker recently published good write up about using MySQL replication. The piece I find missing however is good description of warning about limits of this approach as well as things you need to watch out for. You can call me person with negative mind but I tend to think about limits as well. So […]
Partha Dutta posted pretty interesting post about iSCSI vs SCSI performance using SysBench. This is nice to finally see some iSCSI benchmarks done with MySQL – something we were planning to do for a while but never ended up doing, mainly due to lack of hardware available for tests. It is also good to see […]
If you’re doing significant amount of writes to Innodb tables decent size of innodb_log_file_size is important for MySQL Performance. However setting it too large will increase recovery time, so in case of MySQL crash or power failure it may take long time before MySQL Server is operational again. So how to find the optimal combination […]