Can a bitmap index be used for index-only access?
- From: "Tolkin, Steve" <Steve.Tolkin@xxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Sat, 8 Nov 2008 18:48:37 -0500
Can a bitmap index be used for index-only access?
Suppose there is a single bitmap index defined on two columns A and B in
table T.
Can that bitmap index alone be used for certain queries, without needing
to read any blocks from the base table?
For example these two queries:
Select B from T where A ='a1'
Select A from T where B ='b2'
(An ordinary B-tree index on columns A and B, in that order, supports
index only access on the first query above, but not the second.)
Where, if anywhere, is this described in the Oracle documentation?
Thanks,
Steve
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Steve Tolkin
Vice President
PWI Strategy and Architecture
Fidelity Investments
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