As you may know, flushing in MySQL is an area of my interest, I wrote about it several times, i.e. http://www.mysqlperformanceblog.com/2011/09/18/disaster-mysql-5-5-flushing/ http://www.mysqlperformanceblog.com/2011/03/31/innodb-flushing-a-lot-of-memory-and-slow-disk/ http://www.mysqlperformanceblog.com/2011/01/03/mysql-5-5-8-in-search-of-stability/ In MySQL 5.6 there was implemented a new flushing logic, so I decided to check what do we have now.
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 [...]
Percona XtraDB Cluster: Multi-node writing and Unexpected deadlocks
August 17, 2012 By 17 Comments
Percona XtraDB Cluster (PXC) and the technology it uses (Galera) is an exciting alternative to traditional MySQL replication. For those who don’t know, it gives you: Fully Synchronous replication with a write latency increase equivalent to a ping RTT to the furthest node Automatic cluster synchronization, both incremental and full restores The ability to read [...]
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 [...]
MariaDB 5.3 is released as GA!
March 5, 2012 By 17 Comments
Congratulations to Monty Program and the many community contributors for releasing the GA version of MariaDB 5.3. We were in our annual all-staff meeting last week, so we are a little slow to blog about this and acknowledge the great work that has gone into MariaDB. Better late than never, I hope. Before I discuss [...]
How to Monitor MySQL with Percona’s Nagios Plugins
February 22, 2012 By 11 Comments
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 [...]
Percona Testing: Innodb crash / recovery tests available
December 21, 2011 By Leave a Comment
Not everyone may know this, but there are precious few innodb crash recovery tests available. Some folks have noticed this and asked for something to be done about it, but unfortunately, no tests have been created for the main MySQL branch. The MySQL at Facebook branch has a number of tests that are quite interesting. [...]
Helgrinding MySQL with InnoDB for Synchronisation Errors, Fun and Profit
November 24, 2011 By 2 Comments
It is no secret that bugs related to multithreading–deadlocks, data races, starvations etc–have a big impact on application’s stability and are at the same time hard to find due to their nondeterministic nature. Any tool that makes finding such bugs easier, preferably before anybody is aware of their existence, is very welcome.
Percona Server 5.5.16-22.0
October 16, 2011 By 2 Comments
Percona is glad to announce the release of Percona Server 5.5.16-22.0 on October 14, 2011 (Downloads are available here and from the Percona Software Repositories). Based on MySQL 5.5.16, including all the bug fixes in it, Percona Server 5.5.16-22.0 is now the current stable release in the 5.5 series. All of Percona’s software is open-source and free, all the [...]
Reasons for MySQL Replication Lag
July 29, 2011 By 9 Comments
One common theme in the questions our MySQL Support customers ask is MySQL Replication Lag. The story is typically along the lines everything is same as before and for some unknown reason the slave is started to lag and not catching up any more. I always smile at “nothing has changed” claim as it usually [...]
