It will use the index because of column A in the where clause. It may even
filter the index based on C after a range scan on A. Not 100% sure about
this though.
--
Chuck Hamilton
QVC Inc.
Enterprise Technical Services
Oracle DBA
"Vinayaka
Holla (TSG)" To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
<holla_at_wipro. cc: (bcc: CHUCK HAMILTON/QVC)
co.in> Subject: RE: indexes
Ext: NA
Sent by:
root_at_fatcity.
com
05/11/00
02:26 AM
Please
respond to
ORACLE-L
Hi, I found this in the oracle concept manual
Composite indexes can speed retrieval of data for SELECT statements in
which
the
WHERE clause references all or the leading portion of the columns in the
compos-ite
index. Therefore, the order of the columns used in the definition is
important;
generally, the most commonly accessed or most selective columns go first.
I hope this will help u
Regards
Vinayaka Holla.
* : 5569991 Extn. : 332
Page : 9612-426531
Visit us at http://www.wiproindia.com
----------------------------------------------------------------------------
-----------------------
The trouble with doing anything right the first time
is that nobody appreciates how difficult it was. - Anon
> -----Original Message-----
> From: Webber Valerie H [SMTP:Valerie.H.Webber_at_irs.gov]
> Sent: Tuesday, May 09, 2000 8:40 PM
> To: Multiple recipients of list ORACLE-L
> Subject: indexes
>
> I know this issue has been discussed before but I can't find the answer
in
> my list archives.
>
> If you have a composite index on a table consisting of columns A,B,C in
> that order, will the index be used if I have a query/where clause on
> columns A and C?
>
> I know that it will if I query on A alone or A,B or A,B,C but I can't
find
> documentation about A and C (no B)
>
> Thanks in advance!
> Val
>
> Valerie H. Webber
> Management Systems Designers, Inc
> Valerie.H.Webber_at_m1.irs.gov
> 704-569-1002 x107
>
>
--
Author: Vinayaka Holla (TSG)
INET: holla_at_wipro.co.in
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Received on Thu May 11 2000 - 08:07:43 CDT
