When All Ids Threshold Is Too High; All Ids Threshold Tuning Advice For Single-Enterprise Directories - Netscape DIRECTORY SERVER 6.2 - ADMINISTRATOR Administrator's Manual

Managing Indexes

When All IDs Threshold is Too High

Setting the All IDs Threshold too high can also cause performance problems. An
excessively high All IDs Threshold results in large entry ID lists that must be
maintained and loaded into memory when servicing search requests. An
excessively high All IDs Threshold can eliminate all of the benefits of the All IDs
mechanism (see "Benefits of the All IDs Mechanism," on page 390 for details).
All IDs Threshold Tuning Advice for Single-
Enterprise Directories
Be careful when changing the default All IDs Threshold value for your server. If
you change the threshold to an inappropriate value, you can compromise rather
than improve your server performance. This tuning advice is intended primarily
for single-enterprise directories of up to 80,000 entries.
If your directory size is stable, set the All IDs Threshold to about 5 percent of the
total number of entries stored in your directory. That is, if you have 50,000 entries
in your directory, set the All IDs Threshold to 2,500.
If, you plan to add large numbers of entries to your directory in the near future,
you should carefully consider your All IDs Threshold value. Consider the
following:
• Changing the All IDs Threshold means that you have to rebuild your database.
This is a potentially expensive operation, especially for directories that contain
millions of entries.
• While we recommend setting the All IDs Threshold to 5 percent of your
directory size, you should not see serious performance problems if your All
IDs Threshold is as little as 0.5 percent of your current database size or as great
as 50 percent of your current database size. However, we nevertheless
recommend you aim to stay as close to the 5 percent rule as possible.
You need to balance your current directory needs against future expansion plans to
avoid changing the All IDs Threshold at some later stage (which requires a
database rebuild).
Suppose, for example, that your current directory is 50,000 entries in size.
However, in the next few years you expect your directory to grow 1,000,000 entries.
If you set your All IDs Threshold to 5 percent of 50,000 (2,500), then when your
directory grows to 1,000,000 entries you will have a performance problem. 2,500
entries is too low for a database containing 1,000,000 entries because the lower limit
for a 1,000,000 entry database is .5 percent of 1,000,000, i.e.5,000 entries.
392 Netscape Directory Server Administrator's Guide • December 2003