Re: Binary Index Goes Bananas

A copy of this was sent to Doug Cowles <dcowles_at_bigfoot.com> (if that email address didn't require changing) On Sun, 04 Jul 1999 14:35:01 -0400, you wrote:

>I found a column with very low cardinality - 2 possible values in
>a table of 261,000 or so records. I created a binary index.
>Low and behold, a developer asked me why there would be a problem
>extending index space if they weren't doing any updates..(questionable
>wether they

what is a binary index?

do you mean BITMAP or B*Tree.

If it is a B*Tree -- don't index something with 2 discrete values.

>were or not....but ).
>I never found out wether they were really doing updates or not, but
>after
>adding 500MB of space to the index space, they got the same error.

the same error as what?

>Even if they were doing updates or inserts, doesn't this sound a little
>bit
>like a huge amount of space for a binary index to be taking?
>Do binary indexes traditionally belong in non-updated tables?
>

if you mean bitmap, then the answer is maybe. the maintainence of a bitmap index is higher then that of other index types but you have to trade that off for the increase in performance of queries.
>- Dc.

--
See http://govt.us.oracle.com/~tkyte/ for my columns 'Digging-in to Oracle8i'... Current article is "Part I of V, Autonomous Transactions" updated June 21'st  

Thomas Kyte                   tkyte_at_us.oracle.com
Oracle Service Industries     Reston, VA   USA

Opinions are mine and do not necessarily reflect those of Oracle Corporation Received on Mon Jul 05 1999 - 08:02:06 CDT