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Oracle Directory Server Enterprise Edition Reference 11 g Release 1 (
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Document Information


1.  Directory Server Enterprise Edition File Reference

Software Layout for Directory Server Enterprise Edition

Directory Server Instance Default Layout

Directory Proxy Server Instance Default Layout

Part I Directory Server Reference

2.  Directory Server Overview

3.  Directory Server LDAP URLs

4.  Directory Server LDIF and Search Filters

5.  Directory Server Security

6.  Directory Server Monitoring

7.  Directory Server Replication

8.  Directory Server Data Caching

9.  Directory Server Indexing

Overview of Indexes

System Indexes and Default Indexes

System Indexes

Default Indexes

Types of Index

Presence Index

Equality Index

Substring Index

Browsing Index

Approximate Index

International Index

10.  Directory Server Logging

11.  Directory Server Groups and Roles

12.  Directory Server Class of Service

13.  Directory Server DSMLv2

14.  Directory Server Internationalization Support

Part II Directory Proxy Server Reference

15.  Directory Proxy Server Overview

16.  Directory Proxy Server Load Balancing and Client Affinity

17.  Directory Proxy Server Distribution

18.  Directory Proxy Server Virtualization

19.  Connections Between Directory Proxy Server and Backend LDAP Servers

20.  Connections Between Clients and Directory Proxy Server

21.  Directory Proxy Server Client Authentication

22.  Security in Directory Proxy Server

23.  Directory Proxy Server Logging

24.  Directory Proxy Server Alerts and Monitoring


Types of Index

With the exception of the approximate index, the indexes in this section are used by Directory Server to speed up basic matching rules. This section covers the following index types:

Presence Index

The presence index includes all entries in the database that have a value for a specified attribute, irrespective of that value. The following figure shows a presence index for the nsRoleDN attribute. For information about this attribute, see nsRoleDN(5dsat).

Figure 9-1 Presence Index

image:Illustration of a presence index for the nsRoleDN attribute.

Directory Server uses the value of the entryid attribute to store a reference to the entry. Directory Server retrieves the entry by using the instance-path/db/dbinstance/dbinstance_id2entry.db3 index file, where dbinstance depends on the database identifier.

When Directory Server receives a request to remove an attribute value indexed for presence, it must remove the entry from the presence index for that attribute before acknowledging the update to the client application.

The cost of presence indexes is generally low, although the list of entries maintained for a presence index may be long. When the index list length is small, presence indexes are useful for attributes in a relatively small percentage of directory entries.

Equality Index

The equality index includes all entries in the database that have a specified value for a given attribute. This index requires a value to be specified in the search filter. The following figure shows an equality index for the sn, surname, attribute. The index maintains a list of values for the sn attribute. For information about this attribute, see sn(5dsat).

Figure 9-2 Equality Index

image:Illustration of a equality index for the sn attribute.

When Directory Server receives a request to update an entry indexed for equality, it must do the following tasks before performing the update and acknowledging the update to the client:

The cost of equality indexes is generally lower than for substring indexes, but equality indexes require more space than presence indexes. Some client applications such as messaging servers might rely on equality indexes for search performance. Avoid using equality indexes for large binary attributes such as photos and hashed passwords.

Substring Index

Substring indexes are used for searches on three-character groups, for example, sn=*abc*. The three-character groups are stored in the index. Substring indexes cannot be applied to binary attributes such as photos. The following figure shows a substring index for the SN attribute.

Figure 9-3 Substring Index for the SN Attribute

image:Illustration of a substring index for the SN attribute.

The Directory Server search algorithm includes optimizations for the following searches, however, these searches are more likely to reach the index list threshold:

Directory Server builds an index of substrings according to its own built-in rules. Substring indexes cannot be configured by the system administrator.

When Directory Server receives a request to update an entry that has an attribute indexed for substrings, it must do the following tasks before performing the update and acknowledging the update to the client:

Maintaining substring indexes is relatively costly; the cost is a function of the length of the string indexed. To minimize cost, avoid unnecessary substring indexes, especially for attributes that have potentially long string values such as a description.

Browsing Index

Browsing indexes are also called virtual list view indexes. Browsing indexes are used for search operations that request server-side sorting or virtual list view, VLV, results. By using browsing indexes, you can improve the performance of searches that request server-side sorting of a large number of results. Depending on your directory configuration, the server may refuse to perform searches that request sorting when no browsing index is defined. This prevents large sorting operations from overloading server resources.

Browsing indexes are configured with the following parameters in the vlvSearch(5dsoc) object class, vlvBase(5dsat)vlvScope(5dsat), vlvScope(5dsat), and vlvFilter(5dsat). Browsing index are sorted by the following parameter in the vlvIndex(5dsoc) object class, vlvSort(5dsat).

Browsing indexes are configured in two steps.

  1. The base of the search, the scope of the search, and a filter for the search are configured by the vlvBase, vlvScope, and vlvFilter attributes in the vlvSearch object class.

  2. The name of the attributes that sort the index are configured by the vlvSort attribute in the vlvIndex object class.

The following figure shows a browsing index.

Figure 9-4 Representation of a Browsing Index

image:Illustration of a browsing index.

When Directory Server receives a request to update an entry with a vlvFilter value, it must do the following tasks before performing the update and acknowledging the update to the client:

Approximate Index

Approximate indexes work with the English language only to provide efficient “sounds-like” searches. For example, the approximate index is useful for searching partial names or misspelled names. Directory Server uses a variation of the metaphone phonetic algorithm to perform searches on an approximate index. Because the algorithm is based loosely on syllables, it is not effective for attributes that contain numbers, such as telephone numbers.

International Index

International indexes are also called matching rule indexes. International indexes associate language-specific matching rules with attributes. This index type enables attributes to be sorted and searched for in accordance with the language rules. International indexes use matching rules for particular locales to maintain indexes.

Standard support for international and other types of indexing can be extended by using a custom matching rule server plug-in.