Jason Dusek writes: If you need a search for an attribute to be fast, you should index that attribute if you use back-bdb/hdb. (And I presume, do something equivalent if you use back-sql.) This applies regardless of whether the search is done by a client or an overlay - like refint or unique. DN-valued attributes like secretary and seeAlso are no different from other attributes in this respect. bdb/hdb indexing works on a hash of the attribute value. After scope and indexing (if any) has narrowed down the search, the resulting candidate entries are checked against the filter with the ordinary matching rules. For DN-valued attributes, see above. For the entry DNs themselves, bdb and hdb maintain a dn2id file which maps DN (bdb) or parent+RDN (hdb) to entry-ID. -- Hallvard