About the Oracle Internet Directory Garbage Collection Framework

A garbage collector is a background database process that removes unwanted data from the directory. The Oracle Internet Directory garbage collection framework provides a default set of garbage collectors, and enables you to modify them.

This section contains these topics:

• Components of the Oracle Internet Directory Garbage Collection Framework

• How Oracle Internet Directory Garbage Collection Works

• Garbage Collector Entries

• Change Log Purging in Multimaster Replication

Components of the Oracle Internet Directory Garbage Collection Framework

This section describes the components that make up the Oracle Internet Directory garbage collection framework, namely, the garbage collection plug-in and the garbage collectors themselves.

Garbage Collection Plug-in

Garbage collection in Oracle Internet Directory relies on a garbage collection plug-in that receives requests to manage garbage collectors. This plug-in is installed with Oracle Internet Directory, and is enabled by default. The entry for this plug-in is cn=plugin,cn=subconfigsubentry.

This plug-in has three triggers:

• The DN of the plug-in trigger used to create a garbage collection job is:
  cn=Add PurgeConfig,cn=plugin,cn=subconfigsubentry.

• The DN of the plug-in trigger used to modify a garbage collection job is:
  cn=Modify PurgeConfig,cn=plugin,cn=subconfigsubentry.

• The DN of the plug-in trigger used to delete a garbage collection job is:
  cn=Delete PurgeConfig,cn=plugin,cn=subconfigsubentry.

  See Also: "Oracle Internet Directory Plug-In for Garbage Collection" for a list and descriptions of the attributes of the garbage collection plug-in

Garbage Collectors

Garbage collectors are background database processes that are invoked by the garbage collection plug-in. You can set and manage these behaviors of a garbage collector:

• The subtree in which it purges data

• The time it starts

• The age of the data you want it to purge

• How often it runs

• The type of data you want it to purge

• The number of entries to purge at a time

Predefined Garbage Collectors

A default installation of Oracle Internet Directory includes these predefined garbage collectors:

• Audit log garbage collector--Cleans up obsolete entries created for auditing the directory. The container for this garbage collector is cn=auditlog purgeconfig,cn=purgeconfig,cn=subconfigsubentry.

  See Also: "Audit Log Garbage Collector"

• Change log garbage collector--Cleans up the consumed change log entries in the directory. The container for this garbage collector is
  cn=changelog purgeconfig,
cn=purgeconfig,cn=subconfigsubentry.

  See Also: "Change Log Garbage Collector"

• General statistics garbage collector--Cleans up obsolete entries created by Oracle Internet Directory Server Manageability for monitoring general statistics of the directory. The container for this garbage collector is
  cn=general stats purgeconfig,
cn=purgeconfig,cn=subconfigsubentry.

  See Also: "General Statistics Garbage Collector"

• Health statistics garbage collector--Cleans up obsolete entries created by Oracle Internet Directory Server Manageability for monitoring health statistics of the directory. The container for this garbage collector is cn=health stats purgeconfig,
cn=purgeconfig,cn=subconfigsubentry.

  See Also: "Health Statistics Garbage Collector"

• Security and refresh events garbage collector--Cleans up obsolete entries created by Oracle Internet Directory Server Manageability for monitoring security and refresh events of the directory. The container for this garbage collector is cn=secrefresh events purgeconfig,
cn=purgeconfig,cn=subconfigsubentry.

  See Also: "Security and Refresh Events Garbage Collector"

• System resource events garbage collector--Cleans up obsolete entries created by Oracle Internet Directory Server Manageability for monitoring system resource events of the directory. The container for this garbage collector is cn=sysresource events purgeconfig,
cn=purgeconfig,cn=subconfigsubentry.

  See Also: "System Resource Events Garbage Collector"

• Tombstone garbage collector--Cleans up obsolete entries marked as deleted in the directory. The container for this garbage collector is
  cn=tombstone purgeconfig,
cn=purgeconfig,cn=subconfigsubentry.

  See Also: "Tombstone Garbage Collector"

  Note: Oracle Corporation recommends that you not delete any of the predefined garbage collectors. Deleting one or more of them can result in the proliferation of obsolete data, eventually exhausting all the available disk space. You may, however, modify predefined garbage collectors to customize their behavior.

How Oracle Internet Directory Garbage Collection Works

Figure 22-1 shows an example of a garbage collector operation that purges change log entries.

Figure 22-1 Example: Garbage Collection of Change Log Entries

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As the example in Figure 22-1 shows, the garbage collection process is as follows:

1. An LDAP client sends to the directory server a request for a particular garbage collection operation. The operation could be, for example, to purge the entries of tombstones, change logs, or audit logs.

2. The directory server passes the request to the garbage collection plug-in.

3. The garbage collection plug-in sends the request to the garbage collection engine in the Oracle Internet Directory-designated database.

4. The garbage collection engine triggers the corresponding garbage collector--in this case, the change log garbage collector. The garbage collector runs as a background database process according to the parameters specified in its configuration set entry.

Garbage Collector Entries

Garbage collector entries, each with attributes specifying how it is to behave, are located in the entry cn=purgeconfig, which is located immediately below the entry cn=subconfigsubentry.

See Also: Table B-8, " Garbage Collection Configuration Parameters" for a description of each garbage collector attribute

Figure 22-2 shows the location of these entries.

Figure 22-2 Garbage Collection Entries in the DIT

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Change Log Purging in Multimaster Replication

Change log purging takes place in Oracle Internet Directory in two ways:

• Change number-based

  This is the default method. The replication server purges those changes that have already been applied to all the nodes in a DRG.

• Time-based

  You can run this method to augment change number-based purging. To use this additional method, you set a parameter specifying in hours the lifespan of change log objects. For example, you can set this parameter to purge all change log objects that are 24 hours old. Use this method to prevent the change log from becoming too large.

  Note that this method always respects the rules of change log purging. If, at the specified time, a change has not yet been applied, this method does not purge it.

See Also: "Viewing and Modifying Directory Replication Server Configuration Parameters" "Modifying Directory Replication Server Configuration Parameters by Using Command-Line Tools"