Can a bitmap index be used for index-only access?

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
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http://www.freelists.org/webpage/oracle-l Received on Sat Nov 08 2008 - 17:48:37 CST