Customizing the Schema54 Red Hat Directory Server Deployment Guide • May 2005• Single object classes simplify data design when you have data that you wantto put on more than one type of object class structure.For example, suppose you want preferredOS on both a person and a groupentry. You may want to create only a single object class to allow this attribute.• Avoid required attributes for new object classes.Requiring attributes can make your schema inflexible. When creating a newobject class, allow rather than require attributes.After defining a new object class, you need to decide what attributes it allows andrequires and from what object class(es) it inherits.Strategies for Defining New AttributesAdd new attributes and new object classes when the existing object classes do notsupport all of the information you need to store in a directory entry.Try to use standard attributes whenever possible. Search the attributes thatalready exist in the default directory schema and use them in association with anew object class. Create a new attribute if you cannot find a match in the defaultdirectory schema.For example, you may find that you want to store more information on a personentry than the person, organizationalPerson, or inetOrgPerson object classessupport. If you want to store the birth dates in your directory, no attribute existswithin the standard Directory Server schema. You can choose to create a newattribute called dateOfBirth and allow this attribute to be used on entriesrepresenting people by defining a new auxiliary class, examplePerson, whichallows this attribute.Deleting Schema ElementsDo not delete the schema elements shipped with Directory Server. Unusedschema elements represent no operational or administrative overhead. Bydeleting parts of the standard LDAP schema, you may run into compatibilityproblems with future installations of Directory Server and otherdirectory-enabled applications.
