Oracle Fusion Middleware Administration Guide for Oracle Directory Server Enterprise Edition

Changing the Index List Threshold

Slow searches might be a result of your system index list size exceeding the index list threshold. The index list threshold is the maximum number of values for each index key. To determine whether the index list threshold size has been exceeded, examine the access log. The notes=U flag at the end of an access log RESULT message indicates that an unindexed search was performed. A previous SRCH message for the same connection and operation specifies the search filter that was used. The following two-line example traces an unindexed search for cn=Smith that returns 10,000 entries. Timestamps have been removed from the messages.

conn=2 op=1 SRCH base="" scope=0 filter="(cn=Smith)"
conn=2 op=1 RESULT err=0 tag=101 nentries=10000 notes=U

If your system often exceeds the index list threshold, consider increasing the threshold to improve performance. The following procedure uses the dsconf set-server-prop command to modify the all-ids-threshold property.

ProcedureTo Change the Index List Threshold

You can use DSCC to perform this task. For information, see Directory Service Control Center Interface and the DSCC online help.

  1. Adjust the index list threshold.

    You can adjust your index list threshold at any of the following levels:

    • At the instance level:

      dsconf set-server-prop -h host -p port all-ids-threshold:value
    • At the suffix level:

      dsconf set-suffix-prop -h host -p port suffix-DN all-ids-threshold:value
    • At the entry level:

      dsconf set-index-prop -h host -p port suffix-DN all-ids-threshold:value
    • At the index level, by search type:

      dsconf set-index-prop -h host -p port suffix-DN all-ids-threshold search-type:value

      where search-type is one of the following:

      • eq-enabled equality

      • pres-enabled presence

      • sub-enabled substring

      The all-ids-threshold property cannot be configured for the approximate index.

    You can use DSCC to set the threshold at the index level, by search type. For more information, see the Directory Server online help.

  2. Regenerate the suffix indexes.

    See To Generate Indexes.

  3. If the database cache size was tuned for the old all IDs threshold value and the server has adequate physical memory, consider increasing the database cache size.

    Increase the database cache size by 25 percent of the magnitude of the increase to the all IDs threshold.

    In other words, if you increase the all IDs threshold from 4000 to 6000, you can increase the database cache size by about 12 ½ percent to account for the increase in index list size.

    Database cache size is set using the attribute dbcachesize. Find the optimum size empirically before applying changes to production servers.