----- Original Message -----
Sent: Monday, March 31, 2003 10:34
AM
Subject: Re: index ??
What is the selectivity of column A? How many distinct values?
Is A
nullable? How many rows and blocks in the table
and what are the nr of leaf
blocks and the clustering
factors of the indexes?
At 09:08 AM 3/31/2003 -0800, you wrote:
>I have a table X with unix index on column A ,B and non
unique index on
>A,C,D . The query give below
doesn't use any index .
>
>I thought its due to function nvl being used here , so made a
change in
>query to replace
>
>B = NVL(:b2,B) with
(B=:b2 or :b2 is null ) , but this one also not
>using index . Why if I put an or condition it doesn't use index
while if I
>put and condition it will used ?
>
>IS there any way I can
change query or index so that it starts using index
>( in a better way )
>
>
>
>Thanks,
>
>-ak
>
>
>
>
>
>
>
>SELECT z
>
>FROM
>
>X
>
>WHERE
>
>A = :b1 AND
>
>B = NVL(:b2,B) AND
>
>C= nvl(:b3,C) And
>
>D=nvl(:b4,D)
>
>
>
>
>
>
Wolfgang Breitling
Centrex Consulting
Corporation
http://www.centrexcc.com
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