Lotus Domino Administrator 7 Help - Lotus documentation

Although you can set up servers to use a condensed Directory Catalog, there are several advantages to
using an Extended Directory Catalog instead.
Multiple views
The Extended Directory Catalog uses the same design as the Domino Directory, so it includes multiple
views that sort names in different ways. Regardless of the format of a name, there’s a view in the
Extended Directory Catalog that a server can use to quickly find the name. A condensed Directory
Catalog has one view used for lookups, which you choose how to sort when you configure it. To look up
a name in a condensed Directory Catalog that doesn’t correspond to the selected sort order, the server
uses the full-text index to search for the name, which takes longer than a view search.
Using an Extended Directory Catalog on servers that route mail is a particular advantage, because a mail
server can use views to quickly find an address regardless of the address format. When a mail server
uses a condensed Directory Catalog, mail routing can back up if the Router uses the full-text index to
look up addresses, for example, some Internet addresses, that don’t correspond to the selected sort order.
When a Notes user with a condensed Directory Catalog on the client sends mail to a group, if the client’s
directory catalog doesn’t contain the members of the group, there can be a delay while a server does a
full-text search of a condensed Directory Catalog to look up the members. Delays when sending mail to
groups are not an issue if mail servers use Extended Directory Catalogs.
Ease of application access
Applications can access information in an Extended Directory Catalog as easily as they can in a Domino
Directory. Application access to a condensed Directory Catalog however is restricted by the nature of the
aggregate documents and the number of views.
Multiple-view, enterprise directory
Users can open an Extended Directory Catalog and see an enterprise-wide directory with multiple views
that sort by entry type. In a condensed Directory Catalog, there is only one view to display the different
types of entries.
Groups for database authorization
Servers can use groups in only one directory configured in a directory assistance database, in addition to
the primary Domino Directory for authorizing database access. Using an Extended Directory Catalog for
this purpose, effectively allows servers to use groups in any secondary Domino Directory aggregated in
the directory catalog for database access control.
Remote lookups
Servers use Directory Assistance to locate an Extended Directory Catalog, so you need to replicate the
Extended Directory Catalog only to two or a few strategic servers to which the Directory Assistance
database then points. You can configure failover so that if one replica of the directory catalog is
unavailable, servers can use an alternate.
Each server that uses a condensed Directory Catalog requires a local replica of the directory catalog,
which makes its smaller size less of an advantage overall.
Administrator control over rebuilds
Rebuilding a directory catalog removes all of the existing aggregated information, and then re-aggregates
the information from the source Domino Directories. Since this process is time consuming, the Dircat task
only rebuilds an Extended Directory Catalog when an administrator indicates. Changing almost any field
in the configuration document for a condensed Directory Catalog, by contrast, triggers the Dircat task to
rebuild the directory catalog automatically.
Extended ACL and LDAP access control settings
You can use an extended ACL to refine the overall database access to an Extended Directory Catalog. For
example, you can deny access to sensitive fields, to entire documents associated with a particular part of
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