Re: Bitmap Index

w.r.t

"In your case, i'd definitely say your data has low enough cardinality to
warrant a bitmap index."

I don't have the details to hand, but I've seen and replicated benchmarks that show for querying data, then even up to cardinality of n/2 (n=table rows), then bitmap index outperformed a b-tree index.

Its typically not cardinality that matters - the real benefit of bitmaps comes when you can combine them, or you can scan them *instead* of the table to get data (because they're typically so much smaller). Its this versus the concurrency limitations that you need decide on

hth

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Connor McDonald
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email: connor_mcdonald_at_yahoo.com
web: http://www.oracledba.co.uk



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