Difference Between Aggregates and Compression

Hi,
Can you tell me what is the difference between Aggregates and Compression?
I know ,once compressed data is not available for deletion in request wise
and it moves from  F table to E table .
Aggregates means ,data will move from cube to aggreagates(Baby cubes).
But my query is ,As both of them aggregates the data.which of them should be used. at what situation?
I hope you understood my Query.
Regards.
Naresh.

Hi,
An aggregate is a materialized, aggregated view of the data in an InfoCube. In an aggregate, the dataset of an InfoCube is saved redundantly and persistently in a consolidated form into the database.
Aggregates make it possible to access InfoCube data quickly in Reporting. Aggregates serve, in a similar way to database indexes, to improve performance.
especially in the following cases we create aggregates:
The execution and navigation of query data leads to delays with a group of queries.
You want to speed up the execution and navigation of a specific query.
You often use attributes in queries.
You want to speed up reporting with characteristic hierarchies by aggregating specific hierarchy levels.
For more info on aggregates go though the link below
https://help.sap.com/saphelp_sem320bw/helpdata/en/c5/40813b680c250fe10000000a114084/frameset.htm
Compression creates a new cube that has consolidated and summed duplicate information.
2. When you compress, BW does a group by on dimensions and a sum on measures... this eliminates redundent
information.
3. Compressed infocubes require less storage space and are faster for retrieval of information.
4. Once a cube is compressed, you cannot alter the information in it. This can be a big problem if there
is an error in some of the data that has been compressed.
For more info go though the below link
http://www.sap-img.com/business/infocube-compression.htm
Regards,
Marasa.

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