Last_login plugin and mysql

Hello,

i have problems configuring the last_login plugin with mysql.

I have extended the postfixadmin database with a new field, configured the plugin as described in the wiki.

Finally i got errors: table is not writable, INSERT failed.

Why is the insert required? The plugin should only UPDATE the column for existing rows. Or am i missing some configuration options? Here is my dictionary config:

map { pattern = shared/last-login/$user table = mailbox value_field = x_last_login value_type = uint

fields { username = $user } }

Dovecot: 2.2.27 (c0f36b0)

Kind regards, Thomas