[gnome-db] Re: Thank you for this marvelous work
- From: Jean-Michel POURE <jm poure freesurf fr>
- To: Rodrigo Moya <rodrigo gnome-db org>
- Cc: GDA <gnome-db-list gnome org>
- Subject: [gnome-db] Re: Thank you for this marvelous work
- Date: Sun, 10 Feb 2002 09:49:17 +0100
> And, what are the strict/not-strict functions?
http://www.postgresql.org/idocs/index.php?sql-createfunction.html
The following items may appear in the WITH clause:
iscachable
Iscachable indicates that the function always returns the same result
when given the same argument values (i.e., it does not do database lookups or
otherwise use information not directly present in its parameter list). The
optimizer uses iscachable to know whether it is safe to pre-evaluate a call
of the function.
isstrict
isstrict indicates that the function always returns NULL whenever any of
its arguments are NULL. If this attribute is specified, the function is not
executed when there are NULL arguments; instead a NULL result is assumed
automatically. When isstrict is not specified, the function will be called
for NULL inputs. It is then the function author's responsibility to check for
NULLs if necessary and respond appropriately.
******
Cheers,
Jean-Michel POURE
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