slowly changing dimensions
Moderators: chulett, rschirm, roy
slowly changing dimensions
Can anyone explain about how slowly changing dimensions are implemented in the DW design. And how to implement surrogate keys in real time scenario
pavan
-
rleishman
- Premium Member
- Posts: 252
- Joined: Mon Sep 19, 2005 10:28 pm
- Location: Melbourne, Australia
- Contact:
Pavan,
Take a look in the sdk/KeyMgt folder of Server Routines, there are some routines there that can help with surrogate key allocation.
As for SCD's, depends on whether you want Type 1,2, or 3. If you search this forum you'll find the subject is fairly well covered.
In short, DataStage (Server) does not do the work for you. You have to join the incoming data stream to the existing table, compare each column to see if it has changed using Stage Variables, and use multiple output links to insert/update the target table.
If you are implementing a type 2 SCD, you need to be careful with your Array Size and Transaction Size setting on your database plugin stages. Once again, use the search facility in this forum to find ample information.
Take a look in the sdk/KeyMgt folder of Server Routines, there are some routines there that can help with surrogate key allocation.
As for SCD's, depends on whether you want Type 1,2, or 3. If you search this forum you'll find the subject is fairly well covered.
In short, DataStage (Server) does not do the work for you. You have to join the incoming data stream to the existing table, compare each column to see if it has changed using Stage Variables, and use multiple output links to insert/update the target table.
If you are implementing a type 2 SCD, you need to be careful with your Array Size and Transaction Size setting on your database plugin stages. Once again, use the search facility in this forum to find ample information.
Ross Leishman
-
ray.wurlod
- Participant
- Posts: 54607
- Joined: Wed Oct 23, 2002 10:52 pm
- Location: Sydney, Australia
- Contact: