Optimizer and function based index

From: Seefelt, Beth <Beth.Seefelt_at_TetleyUSA.com>
Date: Thu, 14 Feb 2002 19:11:30 -0800
Message-ID: <F001.004108BD.20020214190324@fatcity.com>

Hi everybody,

I'm hoping someone can help me understand this.

I have this query -

SELECT ORDERID FROM WWW_SHOPCART
WHERE UPPER(MEMBERNAME) ='198917777' ; I added an index on the column UPPER(MEMBERNAME) and it works great.

I have another query -

SELECT ORDERID FROM WWW_SHOPCART
WHERE UPPER(MEMBERNAME) ='198917777' OR UPPER(MEMBERNAME)='1989155555'; and this query will not use the index at all.

I can't understand why the optimizer won't choose to use the function based index when there is an OR clause. I've tried the same query with just MEMBERNAME= and using an index on MEMBERNAME, and the optimizer will use the index if I OR my criteria together.

Any ideas?

Thanks,

Beth

--

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--

Author: Seefelt, Beth
  INET: Beth.Seefelt_at_TetleyUSA.com

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