Directories are primarily read-focused . Typical use of a directory involves a relatively small number of data updates, and a potentially very large number of data retrievals. Directories handle relatively simple transactions on relatively small units of data . For example, an application might use a directory to store and retrieve an e-mail address, a telephone number, or a digital portrait. By contrast, a relational database is designed to handle large and diverse transactions using large data items and many operations.
Directories are location-independent .
Directory applications expect, at all times, to see the same information throughout the deployment environment regardless of which server they are querying. If a queried server does not have the information locally, then the server must either retrieve it or point the client application to it transparently. By contrast, relational database applications generally expect data to be location-specific, that is, to reside on a particular database server. LDAP Version 3 enables vendors to extend existing LDAP operations through the use of mechanisms called controls. It enables retrieval of information about dispersed users and network resources.