Manual:$wgDBtype

Details
Type of database.
 * "mssql" - MS-SQL
 * "mysql" - or MariaDB (Will default to the newer MySQLi driver if enabled on the server.  Otherwise, falls back to the legacy MySQL driver.)
 * "oracle" - ( added in version 1.5 )
 * "postgres" - ( added in version 1.7 )
 * "sqlite" - ( added in version 1.13 )