Percona XtraDB
Percona XtraDB is an enhanced version of InnoDB database engine.
InnoDB features:
- Default storage engine in MySQL 5.5
- InnoDB recovers from a crash or other unexpected shutdown by replaying its logs
- InnoDB automatically groups together multiple concurrent inserts and flushes them to disk at the same time
- ACID compliant
- Transactional support: data integrity is guaranteed in the entire query process
- InnoDB uses row-level locking, as opposed to table locking in MyISAM. InnoDB can modify multiple rows concurrently, where MyISAM can only do one at a time
- Full text search (same as MyISAM)
- Foreign key constraints
- Designed for high performance
- Hot backup: do a full backup while reads/writes are still happening
- Updates are written to the log first, and then the changes are made to the database
XtraDB features:
- Backwards compatible with InnoDB
- Faster performance
- Better scalability
- Better tunability
- More statistics
- Improvements in handing multiple concurrent queries
- NoSQL support (experimental): You can access your data with both NoSQL and SQL statements
- Increased shutdown times
- Corrupted tables are disabled, instead of bringing down the database server
- Can export single tables (n/a in InnoDB)
- Buffer is saved during restarts
- Slow query logs in microseconds instead of in seconds
- Improved SHOW INNODB STATUS
- Improved SHOW PROCESSLIST