Prefetch User Database
======================

Prefetch userdb can be used to combine passdb and userdb lookups into a single
lookup. It's usually used with <SQL> [AuthDatabase.SQL.txt], <LDAP>
[AuthDatabase.LDAP.txt] and <checkpassword>
[PasswordDatabase.CheckPassword.txt] passdbs.

Prefetch basically works by requiring that the passdb returns the userdb
information in <extra fields> [PasswordDatabase.ExtraFields.txt] with 'userdb_'
prefixes. For example if a userdb typically returns 'uid', 'gid' and 'home'
fields, the passdb would have to return 'userdb_uid', 'userdb_gid' and
'userdb_home' fields.

If you're using <deliver> [LDA.txt], you still need a valid userdb which can be
used to locate the users. You can do this by adding a normal SQL/LDAP userdb
*after the userdb prefetch*. The order of definitions is significant. See below
for examples.

LDAP's 'auth_bind_userdn=yes' setting is incompatible with prefetch, because no
passdb lookup is done then. If you want zero LDAP lookups, you might want to
user <static userdb> [UserDatabase.Static.txt] instead of prefetch.

SQL example
-----------

'dovecot.conf':

---%<-------------------------------------------------------------------------
passdb sql {
  args = /etc/dovecot-sql.conf
}
userdb prefetch {
}
# The userdb below is used only by deliver.
userdb sql {
  args = /etc/dovecot-sql.conf
}
---%<-------------------------------------------------------------------------

'dovecot-sql.conf':

---%<-------------------------------------------------------------------------
# NOTE: '\' line splitting works only with v1.1+
password_query = SELECT password, \
  home AS userdb_home, uid AS userdb_uid, gid AS userdb_gid \
  FROM users \
  WHERE userid = '%u'

# For deliver:
user_query = SELECT home, uid, gid FROM users WHERE userid = '%u'
---%<-------------------------------------------------------------------------

LDAP example
------------

'dovecot.conf':

---%<-------------------------------------------------------------------------
passdb ldap {
  args = /etc/dovecot-ldap.conf
}
userdb prefetch {
}
# The userdb below is used only by deliver.
userdb ldap {
  args = /etc/dovecot-ldap.conf
}
---%<-------------------------------------------------------------------------

'dovecot-ldap.conf':

---%<-------------------------------------------------------------------------
# NOTE: '\' line splitting works only with v1.1+
pass_attrs = uid=user,userPassword=password, \
  homeDirectory=userdb_home,uidNumber=userdb_uid,gidNumber=userdb_gid

# For deliver:
user_attrs = homeDirectory=home,uidNumber=uid,gidNumber=gid
---%<-------------------------------------------------------------------------

(This file was created from the wiki on 2011-05-11 04:42)
