Interesting query

From: David Turner <turner_at_tellme.com>
Date: Wed, 27 Jun 2001 11:55:14 -0700
Message-ID: <F001.0033A8DA.20010627110057@fatcity.com>

My users are writing many of their own functions and it is causing performance to suffer
on a few simple queries. For example, I have a query that just selects count(*) from a table. With the function

select count(*) from a_table where a_column = cdk(1234567890);

It takes 5 minutes

By plugging in the result of the cdk function into the query

select count(*) from a_table where a_column = 0987654321;

It take .18 of a second.

How can I tell the optimizer that the result of the function will be the same every time so you don't need to call it for every row? I can do this in the app but it would be cool to know if I can do this on the database side also.

Thanks, Dave

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Author: David Turner
  INET: turner_at_tellme.com

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