RE: Cardinality of indexed columns... how to discover? What is th

> From: Jonathan Lewis [mailto:jonathan_at_jlcomp.demon.co.uk]
>
>
> The answer to the question you asked is to
> check the dba_indexes view for columns
> distinct_keys and num_rows.

Jeeez, guess I hadn't looked hard enough. Thx...

> It is not sensible to change a b-tree index into
> a bitmap index simply because it has a relatively
> small number of distinct values. (Even if you
> have seen an article in Oracle Magazine that
> might suggest otherwise).

Heh. And in other places...

> Bitmap indexes tend to degrade catastrophically
> as the underlying table suffers inserts and deletes
> or gets updates to the indexed column. And the
> probability of contention and deadlock on concurrent
> inserts/updates/deletes is very high.

Good point. This data is mixed tp/dss, so I'll need to make sure that's taken into account.

> Before going much further down your current path,
> you might like to read a couple of articles I've
> written about bitmap indexes at
> www.dbazine.com

Thank you very much.

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Jeremy Pulcifer
  INET: Jeremy.Pulcifer_at_kadiri.com

Fat City Network Services    -- 858-538-5051 http://www.fatcity.com
San Diego, California        -- Mailing list and web hosting services
---------------------------------------------------------------------
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).