Hi Luc,
In applications I've worked on, gender was always near
a 50/50 distribution, in that case an index (btree or
bitmap) or an histogram are not useful.
The case where an index can help on this kind of data
is when you have a value with very few occurences and
your queries are looking for that value most of the
time.
For example if the data has the following distribution
A 35%
B 1%
C 30%
D 34%
If your queries are looking for value B then an index
on the column can help.
- Luc Demanche <ldemanch_at_cetelem.fr> a écrit : >
Hello,
>
> I have an EMP table with a field named GENDER. The
> only two
> possibilities
> for this field is M or F.
>
> What is the best strategy for the cost optimizer
> between:
>
> 1- Create a column histogram on GENDER
> 2- Create a bitmap index on GENDER
>
> We don't use bind variables for GENDER (important
> for histogram).
>
> Thanks in advance.
>
> --
> Author: Luc Demanche
> INET: ldemanch_at_cetelem.fr
>
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Stephane Paquette
DBA Oracle
stephane_paquette_at_yahoo.com
spaquette_at_houra.fr
(33) 01 53 93 06 50
Do You Yahoo!?
Received on Tue May 30 2000 - 04:47:12 CDT
