On 6 Aug 2002 at 15:25, Ivan Prenosil wrote:

> > From: Paul Schmidt
> > If I have the following query:
> >
> > SELECT ORDER_ID FROM ORDERS WHERE ORDER_DATE > '2002-07-01'
> > ORDER BY ORDER_ID DESC;
> >
> > How big a sort file should I guess to end up with, providing neither
> > field is indexed.
>
> Sort file will contain only records that satisfy WHERE criteria (i.e.
> 1000 records). Each row will contain all fields (uncompressed) from
> SELECT clause (i.e. order_id). (and possibly from ORDER BY clause,
> because IB/FB, unlike SQL standard, allows sorting by fields not
> listed in SELECT clause).
>
> Because sort file contains uncompressed data, you can easily end up
> with sort file much larger that whole database (when using long
> VAR/CHAR fields).
>

So the above query would probably result in a 4000 byte or at the worst 12000 byte
file, that's good to know. I wouldn't be surprized if the next version of the standard
doesn't allow an ORDER BY that isn't dependant on the SELECT clause...







Paul Schmidt, President
Tricat Technologies
paul@...
www.tricattechnologies.com