Flush userdb cache entry

Hi all

I have a problem when users change quota in SQL, the change is not reflected in Dovecot immediately so quota_warning is still triggered on some occasions. I think it's because the quota is stored in userdb, and there is no way to flush userdb cache?

Is there a way to flush userdb entries? What controls userdb cache TTL/size? auth_cache entries?

I can't seem to find any documentation on this, sadly :(

Thanks

-- Tom