August 18, 2002 at 11:29 am
I have a partitioned cube - aged partition and current partition (for current day's data). As data comes in during the day it is added to the current day fact table and the current partitioned updated. My question is what happens internally when I move the data out of the current day fact table at night and into the aged fact table and then process both the aged partition and the current day partition (at this point the current day fact table will be empty). Does Analysis Services simply do away with the aggregation tables for the current partition and then rebuild them once new data is added to the current day fact table and that partition is then updated incrementally? I am curious how others have dealt with 'near real time data' outside of using real time cubes with ROLAP. Currently, my dimensions and cube are using MOLAP storage.
Michael Weiss
Michael Weiss
April 13, 2003 at 4:29 pm
Are you asking this because you want to avoid ROLAP (and particularly Enterprise Edition)? I ask because I have an application that relies on this aspect of Ent. Edition and am just about to look at alternatives.
April 13, 2003 at 8:27 pm
What happens to the aggregation data depends upon the method of update. In cases of Full Reprocess or Refresh Data the aggregation data is emptied and recreated. In an incremental update aggregation data is retained and all 'new' data (identified with the Filter clause in the incremental update definition) is added.
So, in your scenario, if you are doing a complete Reprocess nightly aggregation data for both partitions is destroyed then recreated. Presumably, current data is incrementally updated during the day.
One thing to keep in mind: in MOLAP model moving the facts in the relational tables has absolutely no direct effect on Analysis Services - AS has no way of knowing that source data has changed. In ROLAP or HOLAP mode the behavior is different but has some subtle considerations of its own.
Scot J Reagin
Scot J Reagin
sreagin@hitachiconsulting.com
April 14, 2003 at 6:57 am
If you are not changing the structure a Full Process is more than you need to do. A Refresh will get you the same result and will have less impact on anyone who may be connected to the cube.
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