WordPress uses by default MySQL as the Database engine and this is what we have implemented in our DB stack.
Our MySQL stack consists of one primary (master) server and at least two replica (slave) servers configured with automatic failover mechanism in case the primary server fails. The primary server is mainly used for writes (only 1% of the reads are done from the primary server) and the replica servers are used for read queries or for backups.
The default storage engine that we're currently using is MyISAM combined with the default encoding
In case you need a DB dump please check the Access section of our help.