Message-Id: <10735.126075@fatcity.com> From: Amar Kumar Padhi Date: Tue, 9 Jan 2001 08:36:08 +0400 Subject: RE: Go NULL values into an index? This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. ------_=_NextPart_001_01C079F5.AFB88DB0 Content-Type: text/plain; charset="iso-8859-1" Hi, If it is a not null column, you cannot store null now. If you are storing null values in the column on which an index is defined, the index will ignore the records with such instances. So checking for nulls in your query will not use an index. Thanks, Amar Kumar Padhi, Software Consultant -----Original Message----- From: Haunschmidt Andreas VASL/FAS [mailto:Andreas.Haunschmidt@voest.co.at] Sent: Tuesday, January 09, 2001 7:50 AM To: Multiple recipients of list ORACLE-L Subject: Go NULL values into an index? Hi Board Members! Maybe a often posed question, but I dare to ask you directly: If there is a not null column named 'c1' and this column is part of an index - eg.: create (unique) index idx1 on t1(c1,c2...) - will the null values "go" into the index, so that a select * from t1 where c1 is null; or any other select statement can make use of the index ? Thanks in advance! Andreas Andreas -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Haunschmidt Andreas VASL/FAS INET: Andreas.Haunschmidt@voest.co.at 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@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). ------_=_NextPart_001_01C079F5.AFB88DB0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable RE: Go NULL values into an index?

Hi,
If it is a not null column, you cannot store null = now.
If you are storing null values in the column on = which an index is defined, the index will ignore the records with such = instances. So checking for nulls in your query will not use an = index.

Thanks,
Amar Kumar Padhi,
Software Consultant


-----Original Message-----
From: Haunschmidt Andreas VASL/FAS
[mailto:Andreas.Haunschmi= dt@voest.co.at]
Sent: Tuesday, January 09, 2001 7:50 AM
To: Multiple recipients of list ORACLE-L
Subject: Go NULL values into an index?


Hi Board Members!
 Maybe a often posed question,
 but I dare to ask you directly:

 If there is a not null column named 'c1' and =
 this column is part of an index
 - eg.: create (unique) index idx1 on = t1(c1,c2...) -
 will the null values "go" into the = index, so that a
 select * from t1 where c1 is null;
 or any other select statement
 can make use of the index ?
 Thanks in advance!

 Andreas
  Andreas
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Haunschmidt Andreas VASL/FAS
  INET: Andreas.Haunschmidt@voest.co.at

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@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 =