Subject Re: [firebird-support] in vs exist
Author Helen Borrie
At 09:24 AM 19/12/2003 +0100, you wrote:

> > to quote Celko
> > "An EXISTS predicate can use indexes to find.. or fail, whereas the IN
> > predicate ofen has to build the results of the subquery in a working
> >
> > not sure exactly how FB is optimised in this regard
>Celko is talking rubbish here. "can use indexes" -> this is implementation
>defined. How an engine handles whatever statement has nothing to do
>with the logical operator "EXISTS" or "IN".

True, Celko uses Oracle for his examples. He does have a certain blindness
with regard to standard SQL and implementation-specific stuff. He's still
worth paying attention to, esp. in the "Puzzles" stuff.