From: imtiaz sm <imtiaz_sm@yahoo.com>
To: Bruce Momjian <pgman@candle.pha.pa.us>
To: Rajesh Kumar Mallah. <mallah@trade-india.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: BITMAP INDEXES...
Date: Thu, 22 Aug 2002 09:26:57 -0700 (PDT)
Message-ID: <20020822162657.48019.qmail@web21403.mail.yahoo.com> (raw)
In-Reply-To: <200208221430.g7MEUdA27489@candle.pha.pa.us>
Bitmapped indexes are good for weakly constrained queries. Else B+tree indexes are better any day.
Also I guess bitmapped indexes work better when there is an OR predicate on different columns in a query.
Bruce Momjian
wrote:
See the email about bitmapped indexes linked to from the TODO list item
on bitmaps. Bitmap indexes allow arbitrary indexes to be combined into
a single index. Btree indexes can not be combined.
---------------------------------------------------------------------------
Rajesh Kumar Mallah. wrote:
> Hi,
>
> I have learnt from certain texts that bitmap indexes are very useful for
> large DSS (decesion support systems).
>
> bitmap indexes are currently not available in postgresql.
>
> My question is in what way is a normal btree index in pgsql
> inferior to bitmap indexes (found in oracle for example).
>
> is it just in terms of space requirements for performance too?
>
>
> regds
> mallah.
>
>
> --
> Rajesh Kumar Mallah,
> Project Manager (Development)
> Infocom Network Limited, New Delhi
> phone: +91(11)6152172 (221) (L) ,9811255597 (M)
>
> Visit http://www.trade-india.com ,
> India's Leading B2B eMarketplace.
>
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 2: you can get off all lists at once with the unregister command
> (send "unregister YourEmailAddressHere" to majordomo@postgresql.org)
>
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073
---------------------------(end of broadcast)---------------------------
TIP 4: Don't 'kill -9' the postmaster
---------------------------------
Do You Yahoo!?
HotJobs, a Yahoo! service - Search Thousands of New Jobs
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-sql@postgresql.org
Cc: imtiaz_sm@yahoo.com, pgman@candle.pha.pa.us, mallah@trade-india.com
Subject: Re: BITMAP INDEXES...
In-Reply-To: <20020822162657.48019.qmail@web21403.mail.yahoo.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox