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Re: using index

From: David Sisk <davesisk_at_ipass.net>
Date: 1998/10/12
Message-ID: <GpcU1.3019$yo1.57590993@news.ipass.net>#1/1

Actually, this is not quite correct. True in Oracle, B-tree indexes do not store nulls. However, if you issue an "is null" query on a column with a not null constraint enabled, then the normal selection criteria for indexes will be used.

Regards,
Dave

Jurij Modic wrote in message <361fa67c.3119854_at_news.siol.net>...
>On 10 Oct 1998 03:53:51 GMT, paulkcng_at_news.netvigator.com (Ng K C
>Paul) wrote:
>
>>What about ' is null ' and ' is not null '? Will it have the same
 behaviour
>>as ' =" " ' and ' <>" " ' ?
>
>No, ordinary B-tree indexes do not store null values, so "is (not)
>null" condition will never use indexes. Bitmap indexes are different,
>they store bitmaps also for null values, so "is null" predicates can
>use bitmap indexes.
>
>HTH,
>--
>Jurij Modic <jmodic_at_src.si>
>Certified Oracle7 DBA (OCP)
>================================================
>The above opinions are mine and do not represent
>any official standpoints of my employer
Received on Mon Oct 12 1998 - 00:00:00 CDT

Original text of this message

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