Oracle Fusion Middleware Reference for Oracle Directory Server Enterprise Edition

Equality Index

The equality index includes all entries in the database that have a specified value for a given attribute. This index requires a value to be specified in the search filter. The following figure shows an equality index for the sn, surname, attribute. The index maintains a list of values for the sn attribute. For information about this attribute, see sn(5dsat).

Figure 9–2 Equality Index

Illustration of a equality index for the sn attribute.

When Directory Server receives a request to update an entry indexed for equality, it must do the following tasks before performing the update and acknowledging the update to the client:

The cost of equality indexes is generally lower than for substring indexes, but equality indexes require more space than presence indexes. Some client applications such as messaging servers might rely on equality indexes for search performance. Avoid using equality indexes for large binary attributes such as photos and hashed passwords.