When you process MySQL slow query logs using pt-query-digest you can store samples of each query into query_review table and historical values for review trend analysis into query_review_history table. But it could be difficult to easily browse those tables without a good GUI tool. For the visual browsing of tables created by pt-query-digest you may [...]
Wow. My 6 year old MySQL Bug is finally fixed in MySQL 5.6
August 30, 2012 By 2 Comments
I got the message in the morning today about the bug being fixed in MySQL 5.6.6…. which I reported in Early 2006 (while still being with MySQL) and running MySQL 4.1 I honestly thought this issue was fixed long ago as it was indeed pretty annoying. I must say I’m very impressed with Oracle team [...]
Sell-an-Elephant-to-your-Boss-HOWTO
August 28, 2012 By 3 Comments
Spoiler alert: If your boss does not need an elephant, he is definitely NOT going to buy one from you. If he will, he will regret it and eventually you will too. I must appologize to the reader who was expecting to find an advice on selling useless goods to his boss. While I do [...]
Recovery after DROP & CREATE
August 22, 2012 By 1 Comment
In a very popular data loss scenario a table is dropped and empty one is created with the same name. This is because mysqldump in many cases generates the “DROP TABLE” instruction before the “CREATE TABLE”:
1 2 3 4 5 6 7 8 9 10 11 12 | DROP TABLE IF EXISTS `actor`; /*!40101 SET @saved_cs_client = @@character_set_client */; /*!40101 SET character_set_client = utf8 */; CREATE TABLE `actor` ( `actor_id` smallint(5) unsigned NOT NULL AUTO_INCREMENT, `first_name` varchar(45) NOT NULL, `last_name` varchar(45) NOT NULL, `last_update` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP, PRIMARY KEY (`actor_id`), KEY `idx_actor_last_name` (`last_name`) ) ENGINE=InnoDB AUTO_INCREMENT=201 DEFAULT CHARSET=utf8; /*!40101 SET character_set_client = @saved_cs_client */; |
If there were no subsequent CREATE TABLE the recovery would be trivial. Index_id of the PRIMARY index of [...]
Find unused indexes
June 30, 2012 By Leave a Comment
I wrote one week ago about how to find duplicate indexes. This time we’ll learn how to find unused indexes to continue improving our schema and the overall performance. There are different possibilites and we’ll explore the two most common here. User Statistics from Percona Server and pt-index-usage. User Statistics User Statistics is an improvement [...]
Find and remove duplicate indexes
June 20, 2012 By 9 Comments
Having duplicate keys in our schemas can hurt the performance of our database: They make the optimizer phase slower because MySQL needs to examine more query plans. The storage engine needs to maintain, calculate and update more index statistics DML and even read queries can be slower because MySQL needs update fetch more data to [...]
A case for MariaDB’s Hash Joins
May 31, 2012 By Leave a Comment
MariaDB 5.3/5.5 has introduced a new join type “Hash Joins” which is an implementation of a Classic Block-based Hash Join Algorithm. In this post we will see what the Hash Join is, how it works and for what types of queries would it be the right choice. I will show the results of executing benchmarks [...]
Join Optimizations in MySQL 5.6 and MariaDB 5.5
April 4, 2012 By 4 Comments
This is the third blog post in the series of blog posts leading up to the talk comparing the optimizer enhancements in MySQL 5.6 and MariaDB 5.5. This blog post is targeted at the join related optimizations introduced in the optimizer. These optimizations are available in both MySQL 5.6 and MariaDB 5.5, and MariaDB 5.5 [...]
Announcement of Percona XtraDB Cluster 5.5.20 GA release
April 3, 2012 By 11 Comments
I am excited to announce the availability of the GA release of our new product Percona XtraDB Cluster. Percona XtraDB Cluster is a High Availability and Scalability solution for MySQL Users and is based on Percona Server 5.5.20. With this release we make clustering very easy and affordable for everyone. You can convert your existing [...]
Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
This is the second blog post in the series of blog posts leading up to the talk comparing the optimizer enhancements in MySQL 5.6 and MariaDB 5.5. This blog post is aimed at the optimizer enhancement Multi Range Read (MRR). Its available in both MySQL 5.6 and MariaDB 5.5 Now let’s take a look at [...]
