Oracle Pro*C 1.3

• Quoting Ywleung_at_Ouray.Denver.Colorado.Edu to All dated 12-07-93 ***
  > I have a conversation with a gentleman today. He mentioned that there
  > was no way of turning off the optimizer during the compliation of Pro*C
  > programs. To stop the optimizer to use the index, the best we could do is to
  > put a (xx = NULL) in the where clause so that the index will not be used
  > when the select clause is being processed.
  

This is partly true (that is, you cannot turn off the optimizer, but xx = NULL is not an effective way to disable an index) but why the heck would you want to? That's the SQL optimizer you're talking about, NOT the compiler optimizer. To turn off the compiler optimizer, consult your compiler documentation.

> He also mentioned if there are several table in the from clause, the
> rightmost table will be used first when the where clauses are evaluated.

This is 100% wrong. If there are several tables in the from clause, the largest possible index starting with the first arbitrary table (actually based on physical location, so it is NOT smart to rely on consistency).

> Can anyone please provide me some insights on the above statements?

Do no listen to this person any more. <G>

• T.A.G. 2.6f1 Standard
  • Origin: The Lost BBS (1:115/573)