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Message Posted: Fri, 07 Jan 2005 @ 13:27:37 GMT

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There are a few ways to manage change in the warehouse.

One simple way is a LastModifiedDateTime (LM_DT_TM TIMESTAMP(0)) that is part of the ETL process. Of course there are space considerations but this would enable you to capture changes on a daily basis... (oh, don't miss a day or you could miss an update of an update)

Permanent Journals would capture the before or after images of any changes that have occurred and could also be used in part with incremental backups and restores. There is a little overhead but the PJ could be used for an extra layer of data protection as well as logging.

Also there is the actual ETL source data that is being loaded that would have the actual rows that were being updated. In part with the ETL process, append the update rows in your table.

Of course the real question is: "With 15 million rows, what is the purpose for logging the updates?" If you keep the source data you already have the changes. Just keep the source (ETL) files and you can compare these to the production table.

Chris Coffing
Air Force Knowledge Services (AFKS)
Lead DBA Operations & Support
Teradata Certified Master

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