The Cost of Indexing

Although indexes improve search performance, they incur the following costs:

• Slower database modification.

  The more indexes you maintain, the longer it takes to update the database. This is especially true for substring indexes that cause the directory server to generate multiple index files whenever an attribute value is created or changed. For substring indexes, the number of index entries created is proportional to the length of the string being indexed.

• Additional system resources required.

  • Additional disk space

    The more attributes you index, the more files the directory server creates.

  • Additional memory.

    To run more efficiently, the directory server maintatins as many index files as possible in memory; thus, making a greater demand for memory space.

  • Increased disk activity.

    Maintaining indexes that are not frequently accessed creates indexes that might be minimally used and swapped to disk when more frequently accessed index files are paged from disk.