Oracle-L: Re: index on null column

From: Don Granaman <granaman_at_cox.net>
Date: Thu, 27 Mar 2003 20:18:36 -0800
Message-ID: <F001.00574EC0.20030327201836@fatcity.com>

Queries against the non-null values should benefit greatly. Queries on the null values will not use the index since null values are not indexed (at least in single column indexes). It is an old trick to create an index on something like STATUS where the vast majority of records have a NULL (meaning perhaps "PROCESSED") and a small percentage of the records have other non-null values for STATUS ("PENDING","APPROVED", etc.).

Don Granaman
certified OraSaurus

Original Message ----- From: AK To: Multiple recipients of list ORACLE-L Sent: Thursday, March 27, 2003 5:18 PM Subject: index on null column

I have a table with column A. there are 1000000 records in table out of which 500o records has not null in column A rest are null. if i created an index on A, will it benefit .

thanks,
ak

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Author: Don Granaman
INET: granaman_at_cox.net

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