WebSphere

Purging events from the event database

You can run the provided scripts to purge large numbers of events from the event database.

About this task

The default data store plug-in provides a set of utilities you can run periodically to purge large numbers of old events from the event database. These utilities are different from the eventpurge event service command, which deletes events matching specified criteria.

The database purge capability uses the concept of buckets. A bucket is a set of tables used to store events in the event database. The default data store plug-in uses two buckets:

Each event is stored in only one bucket. From the perspective of an event consumer, there is no distinction between the active and inactive buckets; a consumer can query, modify, or delete a specific event without knowing which bucket the event is stored in. The advantage of this approach is that the inactive bucket can be purged using database-specific interfaces without affecting the active bucket; typical event traffic can continue even while the purge operation is taking place.

After the inactive bucket is purged, you can then swap the buckets so that the active bucket becomes inactive and the inactive bucket becomes active. You can swap the buckets only when the inactive bucket is empty.

Although new events are generally stored only in the active bucket, under some circumstances events might be stored in the inactive bucket immediately after the buckets are swapped. The data store plug-in checks periodically to determine which bucket is currently marked as active, but until the next check takes place, some events might continue to be stored in the inactive bucket. Similarly, events sent as part of a batch are all stored in the same bucket, even if that bucket becomes inactive while the batch is still being processed.

If you want to use the fast purge capability, it is your responsibility to determine how frequently to swap buckets or purge the inactive bucket, depending upon event traffic, storage space, archival requirements, or other considerations.


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Timestamp icon Last updated: 22 June 2010


http://publib.boulder.ibm.com/infocenter/dmndhelp/v6r2mx/topic/com.ibm.websphere.cei.z.620.doc/doc/tcei_db_fast_purge.html
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