It seems few use deref overlay. This feature is mentioned on feature list†,
but there is no manual for the overlay; only one line is about it in
ldapsearch(1) manual. In the last years, only one person mentioned it in
2009 on this mailing list, and his question was unanswered.
I observed this is the way it is supposed to work:
$ ldapsearch -E deref=secretary:sn
Would put the surname of the secretary as the value of 'secretary' attribute.
In reality this search extension complains the "control is unavailable in
context". I am afraid loading the model is not enough, it has to be
configured first, somewhere in cn=config, but couldn't find any document.
$ ldapsearch -x -E '!deref=secretary:sn' cn=Betsy secretary
# extended LDIF
#
# LDAPv3
# base <dc=example,dc=com> (default) with scope subtree
# filter: cn=Betsy
# requesting: secretary with dereference critical control
#
# search result
search: 2
result: 12 Critical extension is unavailable
text: critical control unavailable in context
# numResponses: 1
This is how I loaded the module (slapd didn't produce error in log, thus I
consider it is loaded):
$ slapcat -s cn=config | grep -C 8 deref
entryCSN: 20130803010832.965676Z#000000#000#000000
modifiersName: cn=config
modifyTimestamp: 20130803010832Z
dn: cn=module{1},cn=config
objectClass: olcModuleList
cn: module{1}
olcModulePath: /usr/lib/ldap
olcModuleLoad: {0}deref
structuralObjectClass: olcModuleList
entryUUID: cdb88ba8-9131-1032-8334-7700fe3e5919
creatorsName: cn=admin,cn=config
createTimestamp: 20130804091300Z
entryCSN: 20130804091300.138105Z#000000#000#000000
modifiersName: cn=admin,cn=config
modifyTimestamp: 20130804091300Z
Here is the data I am experimenting with, very minimalism:
$ ldapsearch -x objectClass=pilotPerson
# extended LDIF
#
# LDAPv3
# base <dc=example,dc=com> (default) with scope subtree
# filter: objectClass=pilotPerson
# requesting: ALL
#
# David, editors
dn: cn=David,ou=editors,dc=example,dc=com
cn: David
objectClass: pilotPerson
objectClass: person
objectClass: top
sn: Jones
# Betsy, editors
dn: cn=Betsy,ou=editors,dc=example,dc=com
cn: Betsy
objectClass: pilotPerson
objectClass: person
objectClass: top
sn: Shwan
secretary: cn=David,ou=editors,dc=example,dc=com
# search result
search: 2
result: 0 Success
# numResponses: 3
# numEntries: 2
Any hint on how to make it work? Or more importantly, was there anyone using
the overlay at all??
Thanks.
P.S. the email subject intends to guide googlers to land in this discussion.
† http://www.openldap.org/faq/data/cache/645.html
