How To Setup Changelog Purging To Ignore LACNs (Doc ID 827056.1)

Last updated on APRIL 27, 2021

Applies to:

Goal

How to setup changelog purging to only purge changelogs older than 10 days, and completely ignore the LACNs (Last Applied Change Numbers).

Background:
Purges are done based on whether the changelog entry has been processed or not. And if the changelog entry is still there after orclpurgetargetage, it too is purged. However, there is a way around this. One can create a dummy DIP export profile, in which the LACN is never incremented. Then orclpurgetargetage alone will control the deletion.

For details on how purging works, reference the Oracle Internet Directory Administrator's Guide 10g (10.1.4.0.1) > Section 26.1.4 Change Log Purging in Multimaster Replication > Change Log Purging Methods

Also review the Oracle® Identity Management User Reference 10g (10.1.4.0.1) > Section 9.2.342 orclPurgeTargetAge, which says:

This attribute enables time-based purging of change log records. Set this to the number of hours after which old change logs will be purged. Time-based purging respects the change status of replication, but not the change status of other consumers. When time-based purging is enabled, the change log garbage collector purges all change logs that are not needed by replication and that are at least the specified number of hours old.

The default behavior is change number-based purging, meaning this attribute is NULL or set to a value less than zero. Change number-based purging respects the change status of all change log consumers. That is, it does not purge change logs unless they have been consumed by all consumers. In addition, it does not purge change logs until they are 10 days old.

The behavior has changed as a result of the patching of <bug /> in 10.1.4.

• Without the patch, the purge job would check replication, synchronization and provisioning profiles for LACN and check the age of the changes, if orclPurgeTargetAge has been configured.
• With the fix, the purge is executed in two phases:
  • Phase 1: all entries with lower chg_no compared to LACN of all changelog subscribers are purged, regardless of the age
  • Phase 2: Only replication LACN's and the age of the changelog entries are checked. In this phase DIP LACNs are not checked.

If the attribute orclpurgetargetage=0, then changelog entries are purged immediately in phase 2, and if a value is not set, the default of 240 hours is used automatically.

Use the following command to determine the current value of orclpurgetargetage:

Solution

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