Percona Server is a branch of MySQL enhanced with additional features.
SQL
N-ary Storage Model (Row/Record)
Tuple-at-a-Time Model
Disk-oriented
Relational
Shared-Everything
Heaps
http://www.percona.com/software/percona-server
https://github.com/percona/percona-server
@Percona
Percona
US
2006
Commercial, Open Source
MySQL
https://en.wikipedia.org/wiki/Percona_Server_for_MySQL