Line Item: After reading all your links and discussions

Question

From the links and the discussions I was referred to in a previous post, please correct me if I am wrong. I understood that with if a characteristic is going to have several values (defined in that case as "has cardinality"), then it is better to make that characteristic a line item.
It has some advantages as a result of the fact that the line item dimension has no dimension table but only SID table.
1--Does this make loading data faster Or, running queries faster?
2--I also read that "line dimension on means that this dimension becomes part of fact table", can you explain this?
3--Some of the experts said you create line item when the characteristics in the dimension is 20 or 30 % that of the fact table. Is this 20 or 30? And, are we comparing all the characteristics in all the dimensions in the Cube or just the one dimension which we want to make the line item?
4--Also, I get the 20 or 30% of the Dimension but what it being compared to in the Fact Table?
5--I didn't get the cardinality stuff well so any hints other than links will help.
6--Finally, won't this easily make the designer run out of the 13 (16-3 reserved) available dimensions?
7--If the Rule of thumb is dimension table size should be smaller than fact table, and line item dimensions makes this possible, isn't it in the same token killing the ratio of 16 dimension to 1 Fact table in a cube?
8--Is this a consideration after data has been loaded into Cubes or during the design phase of the Cube?
9--If this consideration is applicable only when there is data then how can you factor this into your design? How to wait until you are in trouble to fix the problem?
Thanks

Answer 1

HI Caud,
1] Query reading performance will be improved. As it can access only Master data table and Fact table.
Setting it as a Line Item dim also causes a b-tree index to be built instead of a bitmap index, but also embeds SID directly in the fact table, eliminating the dimension table.
2] Line item Diemsion- when ever ur Dimension table contains a single Char then it is better to join ur master data table with the Fact table. So there will be connection with SID.
3]U chooses the line item when ever there is a high cardinality. i.e if ur DIM table is 10%of Fact table then u will go with the Line item Dim.
the percentage is w.r.t the number of records.
4] its total number of records.
5]Cardinality creates indexes on the Dimension table entries and there by you would see an improvement in performance.
With Cardinality, you can assign a Dimension containing Multiple Characteristics
6] It depends based ur business requirement and the type of data that u use.
8] It is before loading into the cube.
9]it is better to design at the initial stage it self.
Refer this link..
http://help.sap.com/saphelp_nw04/helpdata/en/a7/d50f395fc8cb7fe10000000a11402f/frameset.htm
Regards-
MM
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Message was edited by: vishnuC