OR Statement causes long runtime

[roedelfroe]

Hi all,

following problem:

Statement:

select * from some_table
where (A OR B)
AND C
AND D

This statement was running 5 hours. In my opinion (A OR B) is causing this problem.

select * from some_table
where
A
AND C
AND D
OR
B
AND C
AND D

which is logically the same will take only a few seconds to execute.

After all, I would prefer the first statemnt (because of legibility and to keep the code as small as possible).

Any hints, how I could make the first statement faster?

Thx in advance

Roland

 

[lewisp]

What is your OR statement in the first example? Can you consider using DECODE or IN, or is it more complex?

 

[sem]

Can you send execution plans for both statements? Is your statistics up to date?

Regards, Dima

http://seminihin.narod.ru

 

[BJCooperIT]

There are many possiblilities based on your indexes. Without more information all I can offer is to try:

select * from some_table
  where A
  AND C
  AND D
union all
select * from some_table
  where B
  AND C
  AND D

Hope this helps!


^{Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw}
Consultant/Custom Forms & PL/SQL - Oracle 8i & 9i - Windows 2000