diff b/w aggretation and compresion?

[Former Member]

any one give me the diff b/w aggretation and compresion?,in both sinero we aggregate data, and why rool up, after rool up again we do compresion , i dont under stand taht

[Former Member]

Hi,

Aggregates are smaller cubes ie The data is stored in diff tables rather than the Infocube Fact tables with the selected char.s only.

In the compression we are moving F-fact table data in the cube to E-fact table of the same cube eliminating the request id.

So that no, of records will be reduced in the cube.

Rollup is based on the request id. So we have to do Rollup before compression because Compression eliminates the request id.

REDDY

[Former Member]

Hi,

Aggregation:

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 on the database. Aggregates allow quick access to InfoCube data during reporting.

http://help.sap.com/saphelp_nw70/helpdata/EN/26/4bc0417951d117e10000000a155106/frameset.htm

Compression:

When you load data into the InfoCube, entire requests can be added at the same time. Each of these requests has its own request ID, which is included in the fact table in the package dimension. This makes it possible to pay particular attention to individual requests. However, the request ID concept can also cause the same data record (where all characteristics are the same except the request ID) to appear more than once in the fact table. This can be eliminated by Compressing the cube.

http://help.sap.com/saphelp_nw70/helpdata/EN/ca/aa6437e7a4080ee10000009b38f842/frameset.htm

First you have to build the Aggregates and do the Compression.

If you do Compression first then what happens is that it deletes all the Requests and transfers records from F Table to E Table.