RE: [HACKERS] NULL handling question

I would like to have a C function and/or stored procedure that can accept a
null parameter value and return a non-null value. 

Thanks, Michael
-----Original Message-----From:    D'Arcy" "J.M." Cain [SMTP:darcy@druid.net]Sent:    Monday, March 29, 1999 10:27
AMTo:   lockhart@alumni.caltech.eduCc:    neko@kornel.szif.hu; hackers@postgreSQL.orgSubject:    Re: [HACKERS] NULL
handlingquestion
 
Thus spake Thomas Lockhart> > I don't seek this in the source, but i think, all function, who
take a > > NULL value as parameter can't return with a NOT NULL value.> > But why?> > Postgres assumes that a NULL
inputwill give a NULL output, and
 
never> calls your routine at all. Since NULL means "don't know", there is
a
Actually, the problem is that it does call the function.  After itreturns it throws away the result and so the effect
isthat the
 
functionnever gets called but in the meantime, the function has to deal withNULL inputs for nothing.  This has been
hangingaround since the
 
lastrelease.  I looked at the dispatch code but it wasn't very clear
wherewe have to put the test to do this correctly.  Maybe we can get it
cleanedup before release this time.

> strong argument that this is correct behavior.
I agree but recently I said that there was no stored procedures in
PostgreSQLand someone corrected me pointing out that functions with no return
werein effect stored procedures.  Do the same arguments apply?  If a
procedureis passed a NULL argument, should the side effects be bypassed?
-- D'Arcy J.M. Cain <darcy@{druid|vex}.net>   |  Democracy is three
wolveshttp://www.druid.net/darcy/                |  and a sheep voting on+1 416 424 2871     (DoD#0082)    (eNTP)   |
what'sfor dinner.