bitmap index and star transformation must be single colum?
- From: amonte <ax.mount@xxxxxxxxx>
- To: Oracle-L Group <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 7 Oct 2010 09:25:19 +0200
Hi
I am reading 11.1 and 11.2 Data Warehousing Guide and where it explains
about using star transformation with bitmap index in both release it states:
*A prerequisite of the star transformation is that there be a single-column
bitmap index on every join column of the fact table. These join columns
include all foreign key columns.*
Is it saying that bitmap index cannot be composite?
So for example if fact table has FK against dimension such as
fact.c1 ----> dim1.c1
fact.c2 ----> dim1.c2
We cannot create a bitmap index on fact.c1 and fact.c2? But we can create
two seperate bitmap index each for each fact table column?
Alex
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