MySQL
EXPLAIN – An essential tool for MySQL developers.
Just recently I came across the presentation “Bend SQL to your will with EXPLAIN” by Ligaya Turmelle via the Linked In – MySQL Speakers and Presenters group. Slides available at Slideshare .
Read moreCalculating your database size
I generally use the following MySQL INFORMATION_SCHEMA (I_S) query to Calculate Your MySQL Database Size . This query and most others that access the MySQL INFORMATION_SCHEMA can be very slow to execute because they are not real tables and are not governed by physical data, memory buffers and indexes for example but rather internal MySQL data structures.
Read moreUnderstanding Innodb Transaction Isolation
The MySQL Innodb storage engine provides ACID compliance, the ‘I’ being isolation. There are four states defined in MySQL with the tx_isolation system variable, READ-UNCOMMITTED, READ-COMMITTED, REPEATABLE-READ and SERIALIZABLE. Generally MySQL installations do not modify the default value of tx_isolation = REPEATABLE-READ, however I have seen with a number of clients the default value has been changed to READ-COMMITTED.
Read moreSELECT INTO DUMPFILE
While learning a new ORDER BY syntax recently, as a diligent architect/DBA I reviewed the documentation. What I also found in the SELECT syntax which I did not also know was the keyword DUMPFILE.
Read moreIdentifying Resource Bottlenecks – Disk
With a discussion on identifying CPU and Memory bottlenecks achieved, let us now look at how Disk can affect MySQL performance. One of the first steps when addressing a MySQL performance tuning problem is to perform a system audit of the physical hardware resources (CPU,Memory,Disk,Network), then identify any obvious bottlenecks in these resources.
Read moreMy favorite MySQL data type – DECIMAL(31,0)
It may seem hard to believe, but I have seen DECIMAL(31,0) in action on a production server. Not just in one column, but in 15 columns just in the largest 4 tables of one schema.
Read moreMySQL SHOW PRIVILEGES
Some days you learn about MySQL commands even without knowing about them. Today I wanted to check the privileges a user had because they did not have permissions to drop a view.
Read moreEngine agnostic MySQL test cases
Mark writes Now we all need the storage-engine independent test suite . I could not agree more. I have made comments about this probably as early as 4 years ago, and both before and while working for MySQL Inc.
Read moreHow do I create a simple MySQL database
I was asked this question recently “I am wanting to create a simple MySQL database consisting of 5 tables”? While it’s easy to tell people to RTFM, the question does warrant an answer for the MySQL beginner to provide a more specific guidance as to where to start, and what to do.
Read moreHow do I find the storage engine of a MySQL table
This seems quite a trivial question, but developers don’t often know what a MySQL storage engine is and how to determine what storage engine is used for a table. The first choice is to describe the table with the DESC[RIBE] command.
Read moreMonitoring MySQL – The error log
It is important that you monitor the MySQL error log. There are a few different options available for defining the details of the log. If not specified the default is [datadir]/[hostname].
Read moreExplain this
The EXPLAIN command is an important tool to review how a SQL query is executed and in this example includes what indexes are used. By adding a covering index I ended up with the following EXPLAIN plan I was unable to explain.
Read moreMySQL Replication 102
One of the most asked questions is how to setup MySQL replication. The MySQL Reference Manual provides a good Replication How To as a starting guide on MySQL Replication 101.
Read moreWhere can you find MySQL Events?
As a frequent traveler for my MySQL consulting (last 4 weeks were Sydney, San Francisco, New York and Vancouver), I like to keep abreast of any local tech event that includes MySQL that I may be able to attend.
Read more