Directory Server uses indexes to speed up search operations by associating lookup information with Directory Server entries. During a search operation, Directory Server uses the index to find entries that match the search key . Without an index, Directory Server must check every entry in a suffix to find matches for the search key.
Indexes are stored in database files, and are created and managed independently for each suffix in a directory. Each index file contains all of the indexes defined in the suffix for a given attribute. For example, all indexes maintained for the cn attribute are stored in the databaseName_cn.db3 file. When an indexed entry is modified, Directory Server updates the index files.
Directory Server supports the following types of indexes:
Default indexes to improve search performance or support searches performed by other applications. Default indexes are added when a suffix is created.
System indexes to help Directory Server to function properly and efficiently.
User indexes, added when a user creates an attribute or defines a new index.