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Re: Comparison of Function-Based and regular indexes

From: Connor McDonald <connor_mcdonald_at_yahoo.com>
Date: Thu, 11 Nov 2004 20:02:50 +0800
Message-ID: <419354EA.5AA7@yahoo.com>


Bruno wrote:
>
> Hi,
>
> Can someone point me to a resource or share their experience on this subject?
>
> What is the difference in response time for SELECT, INSERT and UPDATE on a table with regular index on a varchar2 column (all values uppercase) and the same table with the same index but this time function-based, with UPPER function on the same column (with mixed case values).
>
> Will INSERT and UPDATE operations be slower with the function-based index? I would assume they should be, but am having hard time finding any resources. I am about to run some benchmarks on this, but am looking for a third-party opinion :-)
>
>
>
> Thanks!
>
> Bruno

Its predominantly related to the cost of the function. If its a low cost expression, then you'll hardly notice the difference. If its (say) a custom plsql function that does 1000 things within in, then you'll certainly notice it.

hth
connor

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Connor McDonald
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Received on Thu Nov 11 2004 - 06:02:50 CST

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