I thought that Bitmap indexes were specifically designed for situations
such as M-F where there was low cardinality across (potentially) large
amounts of data.
>----------
>From: paquette stephane[SMTP:stephane_paquette_at_yahoo.com]
>Sent: May 30 2000 11:51
>To: Multiple recipients of list ORACLE-L
>Subject: Re: Histogram VS bitmap index
>
>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 ecrit : >
>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
>>
>> Fat City Network Services -- (858) 538-5051 FAX:
>> (858) 538-5051
>> San Diego, California -- Public Internet
>> access / Mailing Lists
>>
>--------------------------------------------------------------------
>> To REMOVE yourself from this mailing list, send an
>> E-Mail message
>> to: ListGuru_at_fatcity.com (note EXACT spelling of
>> 'ListGuru') and in
>> the message BODY, include a line containing: UNSUB
>> ORACLE-L
>> (or the name of mailing list you want to be removed
>> from). You may
>> also send the HELP command for other information
>> (like subscribing).
>
>
>=====
>Stephane Paquette
>DBA Oracle
>stephane_paquette_at_yahoo.com
>spaquette_at_houra.fr
>(33) 01 53 93 06 50
>
>__________________________________________________
>Do You Yahoo!?
>Kick off your party with Yahoo! Invites.
>http://invites.yahoo.com/
>--
>Author: =?iso-8859-1?q?paquette=20stephane?=
> INET: stephane_paquette_at_yahoo.com
>
>Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
>San Diego, California -- Public Internet access / Mailing Lists
>--------------------------------------------------------------------
>To REMOVE yourself from this mailing list, send an E-Mail message
>to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
>the message BODY, include a line containing: UNSUB ORACLE-L
>(or the name of mailing list you want to be removed from). You may
Received on Tue May 30 2000 - 05:32:56 CDT
