SQL statement with Function returns slow in Interactive Report

Question

I have an Interactive Report that returns well but when I add in a function call in the where clause that does nothing but return a hard coded string of primary keys and is compared to a table's primary key with a like operator the performance tanks. Here is the example:
get_school2_section(Y.pk_id,M.pk_id,I.section,:P577_SECTION_SHUTTLE) LIKE '%:' || I.pk_id || ':%'
I have the values hard coded in the return of the function. There are no cursors run in the function, there is no processing done in the function. It only declares a variable. Sets the variable, and returns that variable back to the SQL statement.
I can hard code the where clause value to look like this:
':90D8D830A877CCFFE040010A347D1A50:8ED0BBFDEAACC629E040010A347D6471:9800B8FDBD22B761E040010A347D0D9A:' LIKE '%:' || I.pk_id || ':%'
This returns fast. When I add in the function call which returns the same hard coded values, the page goes from returning in 1 to 2 seconds to 45 or more seconds.
Why does adding a simple function call into the where clause cause such a deterioration in performance.
Edited by: alamantia on Aug 17, 2011 7:39 AM
Edited by: alamantia on Aug 17, 2011 7:40 AM

Answer 1

So you are telling me that the where clause with a function call will NOT run the function on every row? Please explain that to me further?
if you have code that is the following:
select a,b,c from a_table where a > 2 and b < 3 and function_call(c) > 0You are telling me that Oracle will NOT call that function on EVERY row it tries to process in the select?
Thank you,
Tony Miller
Webster, TX
I cried because I did not have an office with a door until I met a man who had no cubicle.
-Dilbert
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