Service manual

Costs: How Updates Affect Indexes
132 Sun ONE Directory Server Installation and Tuning Guide • June 2003
When Directory Server receives an update request for an entry matching a
vlvFilter value, it must determine whether the entry must be removed from the
index or not, determine the correct position of the entry in the list, and must then
carry out any necessary modifications before returning acknowledgement of the
update to the client application.
Approximate Indexes
Directory Server maintains approximate indexes using a variation of the metaphone
phonetic algorithm.This algorithm breaks down an attribute string value into a
rough approximationof its English phonetic pronunciation. Values to match in
incoming search requests are handled using the same algorithm. As the algorithm
is based loosely on syllables, it is not effective for attributes containing numbers
such as telephone numbers.
Thealgorithm generatesa targetstring foreachattributevalue string. Costsfor this
“sounds like” indexing of English-language strings are therefore similar to those
for equality indexing.
International Indexes
International indexes use matching rules for particular locales to maintain indexes.
Costs for such indexes therefore resemble costs for substring and equality indexes.
Using a custom matchingrule server plug-in, you can extend standard support for
international and other types of indexing. Refer to the Sun ONE Directory Server
Plug-In API Programming Guide for more information on custom matching rule
plug-ins.
Example: Indexing an Entry
Consider a user entry as shown in being added to a suffix indexed for equality on
uid, for equality, substring and approximate searches on Common Name (cn)and
surname (
sn)attributes, for equality searches on the mail attribute, for equality
and substring searches on the
telephoneNumber attribute, and for substring
searches on the
description attribute.