WHERE Clause and Performance

[Benouche]

Hello,

a little question on the Where Clause.

Is there performance difference between the 2 following:
WHERE test1 AND test2 (solution 1)
WHERE test2 AND test1 (solution 2)

As test2 require many operations while test1 few, is (solution 1) best or simply equal ?

 

[jimbopalmer]

This will be very database specific, in Oracle the cost based optimiser wil analyze the where clause in one direction while the rule based optimzer analyzes it in the other direction. I tried to remain child-like, all I acheived was childish.

 

[Benouche]

so what ? (I run Oracle8i)

 

[angiole]

I would recommend you run an Explain Plan so that Oracle can tell you the execution path.

If one of the predicates in the Where statement should use an index according to your knowledge, and the Plan shows it does not, well, go figure ... AA 8~)

 

[fmorel]

I don't think it makes a difference.
In Oracle, with RBO (Ruled based Optimizer), the order of the tables in the "from" clause makes a difference.

Regards

 

[fmorel]

I don't think it makes a difference.
In Oracle, with RBO (Rule based Optimizer), the order of the tables in the "from" clause makes a difference.

Regards