Can't connect to database

[Ken Wright]

Dovecot has been giving me problems for the past week or so.  Today the
error log showed me this:

Jan  2 13:33:39 grace dovecot: auth-worker(3250): Error:
mysql(localhost): Connect failed to database (postfix): Can't connect
to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)
- waiting for 5 seconds before retry

The socket is there, showing full permissions (rwx for owner, group,
and rest of the universe) so I can't understand why dovecot can't
connect.

Is there anyone who can help?

Ken