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Re: STATE columns - bitmap index or not?

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Tue, 13 Feb 2001 07:40:13 -0000
Message-ID: <982049805.15759.0.nnrp-10.9e984b29@news.demon.co.uk>

Actually, there is a worked example in my book which demonstrates that clustering and rows per index value is more important.

The actual example has 2,800 rows and a
cardinality of 560 (i.e. 5 rows per value).

Of course, the point up rate of change is very important - bitmaps on tables
subject to almost any change tend
generate huge amounts of contention,
and fragment very badly.

--
Jonathan Lewis
Yet another Oracle-related web site:  http://www.jlcomp.demon.co.uk

Practical Oracle 8i:  Building Efficient Databases
Publishers:  Addison-Wesley

Reviews at: http://www.jlcomp.demon.co.uk/book_rev.html



Howard J. Rogers wrote in message <3a88e233_at_news.iprimus.com.au>...



>But that aside, I believe there was a post ages ago (either from Jonathan
>Lewis or Steve Adams, but my brain may be failing me utterly, and it could
>have been someone completely different) that suggested a cardinality of 50
>is not unreasonable (it seems just a trifle high to me -I always teach a
>cardinality of 20 is where it starts to get dubious).
Received on Tue Feb 13 2001 - 01:40:13 CST

Original text of this message

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