E vs F table Sap Bi

                       E-Table vs F-Table  
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Difference between 'F' fact table & an 'E' Fact table?

A cube has 2 fact tables - E and F. When the requests in the cube are not compressed the data exists in the F fact table and when the requests are compressed the data lies in the E fact table.

When the requests are compressed all the request ids are lost (set to NULL) and you would not be able to select/delete the data by request id. The data in the E fact table is compressed and occupies lesser space than F fact table.

When you load a data target, say a cube, the data is stored in the F fact table. If the cube is compressed, the data in the F fact table is transferred to the E fact table.
 
The F-table uses bitmap indexes the E-Table uses btree. indexes. Index, Primary Index (The primary index is created automatically when the table is created in the database.).  Secondary Index (usually abap tables), Bitmap Index(Bitmap indexes are created by default on each dimension column of a fact table), and B-Tree Index.


Does anybody know what the compression factor is between the F-table and the E-table?
I.e. when you move 100 rows from the F-table, how many rows will be added to the E-table?

There is no conversion factor. All the request id's are deleted when you compress the Cube and the records are aggregated based on the remaining dim id's.

Ex- suppose there is only one customer with C100 is doing Transactions & in 100 requests there are 100 records.
Then when you eliminate the request all records are aggregated to 1 record.

If there are 100 customers and you enterd each customer data in each request. Then when you do compression there will be 100 records still because the customer no. Varies.


Bex access the records from F-table or E- Table of InfoCube?

Bex access both F and E fact tables. If data exists in both tables, it picks from both.

If the cube is not compressed it takes from F table, if fully compressed it takes from E table, partial compression - both F and E.


If Accessing from E- table is true, do we have to move the records from F table to E table in-order to make the records available for reporting?

Data is automatically moved from F to E fact table when you compress the data in the cube. You can do this in the cube manage->collapse tab.

E table will have data once you do compression, and compression is not mandatory for all the cases. try using aggregates for reports.


When we do roll-up in InfoCube maintenance, records are moved to aggregates? or moved from F table to E table?

Roll-up adds the copy of records from F or E table to the aggregate tables. The records are not moved from F or E.