ResolveDriver attempts to inspect db and determine which Driver should be used.

Max length of hostname.

Max length of locker id.

Max length of a named mutex.

MysqlDriver is the mysql specific Driver implementation.

PostgresDriver is the postgres specific Driver implementation.

Driver is the interface that must be implemented by the database-based locker.

Execer is the contract used when executing statements against the DB.

Execer is the contract used when querying against the DB.

QueryExecer is both an Execer and a Queryer.