Manual:$wgDBtype/en

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)