Hi,

At December 18, 2003, 20:41, Alan McDonald 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 table"

> not sure exactly how FB is optimised in this regard

FB 1.5 will use an index if it exists, and also depending on what is
in the IN predicate clause. I can't say precisely when an index would
be used, because I've always used the EXISTS predicate and never came
across a scenario where I had to use the IN predicate.

--
Best regards,
Daniel Rail
Senior System Engineer
ACCRA Group Inc. (www.accra.ca)
ACCRA Med Software Inc. (www.filopto.com)