Cardinality

[Former Member]

Is the High Cardinality field related to the Line Item field? What I mean to ask is if a Dimension does not have the LineItem value checked but has the High Cardinality checked does this make sense? If so why, if not why not. Thanks in advance

[Former Member · Accepted solution]

Seach the forum on cardinality, think you'll find some discussion.

Some of the options on index type that get created are DB dependent - that is - not available in all the DBs that BW runs on.

With Oracle DB, setting the Cardinality option causes a b-tree index to be built instead of a bitmap index even if it is not a line item dim.

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.

Added mention of embedding SID in fact table for Line Item dimension.

Message was edited by: Pizzaman

[Former Member · Accepted solution]

Thank you guys I have awarded points

[Former Member]

Hi Harpal,

It does make sense to have only cardinality flag checked and not line item dimension flag. You might have other chars in the dims liked to each other so you have to keep it as normal dimension, but still might grow huge. In this case, you can check 'Cardinality Heights' flag to have better index types chosen at the DB level.#

Regards,

Sree

[Former Member]

Hi,

With Line Item Dimension, you can assign ONE Dimension to only one characteristic.

With Cardinality, you can assign a Dimension containing Multiple Characteristics.

The scenario totally depends on what is the size of the Dimension Table w.r.t Fact Table. If it is greater than 10% of Fact Table then you need to consider about these.

Cardinality creates indexes on the Dimension table entries and there by you would see an improvement in performance.

There are a couple of forums in SDN which have good discussions in regards to these.

Regards,

GPK.