RE: User defined SQL function

Hi Franco
It looks like (I'm guessing) that the culprit is the udf myfunction
Have you tried creating a work file
Insert into work_file
(select field1 from mytable
where field2 like 'A%')

Then running a separate SQL over work_file
select
myfunction(field1) from work_file where field2 like 'A%'
and see what the times are like
Alan Shore
Programmer/Analyst, Direct Response
E:AShore@xxxxxxxx
P:(631) 200-5019
C:(631) 880-8640
"If you're going through Hell, keep going" - Winston Churchill


-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Franco Lombardo
Sent: Monday, May 14, 2012 1:03 PM
To: midrange-l@xxxxxxxxxxxx
Subject: User defined SQL function


Hi all,

I have an SQL problem. I have a query like this

select
myfunction(field1) from mytable where field2 like 'A%'

The table mytable
is really big, the selection like 'A%' extracts quickly only a few records, while myFunction is a bit slow A "good" execution plan should extract records and apply myFuntion to the results, but the system applies myFunction to the whole table, and then it does the filter...it takes forever....

I
tried to rewrite my query this way:

with x as (select field1 from mytable
where field2 like 'A%')
select myfunction(field1) from x

but it's
still very slow!

Can you help
me?

Bye

Franco


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http://www.francolombardo.net
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Java, As400.....
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