If you read back on my earlier responses, you'll note I mentioned
"normalization" of the values.
Basic breakdown:
If an attribute is defined in the schema with an EQUALITY rule, then
the values get normalized.
If an attribute is defined in the schema without an EQUALITY rule,
there are no normalized values.
Case a: Normalized values
You can use changetype: modify + add to add value(s) to an attribute
because slapd has the knowledge with which to check for duplicate
values based on the EQUALITY rule.
Case b: No normalized values
You cannot use changetype: modify + add to add value(s) to an
attribute because slapd has no knowledge about whether or not there
are duplicate values. You must use changetype: modify + replace.
I.e., if I have:
dn: uid=joe,cn=people,dc=example,dc=com
mail: joe@example.com
And in this case "mail" has no EQUALITY rule, if I try to do:
dn: uid=joe,cn=people,dc=example,dc=com
changetype: modify
add: joe@example2.com
it will fail, because there are no normalized values that slapd can
use to ensure I'm not adding a duplicate to what already exists.
Instead, I must do:
dn: uid=joe,cn=people,dc=example,dc=com
changetype: modify
replace: mail
mail: joe@example.com
mail: joe@example2.com
Hope that helps.
--Quanah