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* Rules: passing new/old to functions
@ 2003-06-22 20:28 Gunter Diehl <gdid@gmx.de>
0 siblings, 1 reply; 2+ messages in thread
From: Gunter Diehl @ 2003-06-22 20:28 UTC (permalink / raw)
To: pgsql-sql
How to pass the special variables new / old to functions?
e.g. I'd like to to something like this (v is a view):
create funtion f1(v, v) returns void as '...'
create rule vupt as on update to v do instead select f1(new, old)
While accepting this definitions, pg says it can not handle "whole-tuple
references" at runtime.
using: select f(new) from new doesn't work either: pg says relation new
doesn't exist.
Since I need to handle tables with more than 20 columns, it would be uggly
if I had to pass every single value to the function as follows:
select f1(new.1, ..., new.n, old.1, ..., old.n)
create function f1(typeof 1, ..., typeof n, typeof 1, ..., typeofn)
I'd be glad for any kind of suggestion.
regards,
Gunter
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^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: Rules: passing new/old to functions
@ 2003-06-27 03:49 Tom Lane <tgl@sss.pgh.pa.us>
parent: Gunter Diehl <gdid@gmx.de>
0 siblings, 0 replies; 2+ messages in thread
From: Tom Lane @ 2003-06-27 03:49 UTC (permalink / raw)
To: Gunter Diehl <gdid@gmx.de>; +Cc: pgsql-sql
Gunter Diehl <gdid@gmx.de> writes:
> create funtion f1(v, v) returns void as '...'
> create rule vupt as on update to v do instead select f1(new, old)
> While accepting this definitions, pg says it can not handle "whole-tuple
> references" at runtime.
FWIW, the "old" case works fine. "new" doesn't work so well because the
new row hasn't been formed into a tuple at the point where the rule
runs; it only exists as a list of variables. (This is a rather handwavy
explanation, but I think it captures the key point.) While this could
probably be fixed with some effort, I doubt it's going to happen soon.
Is there any chance of doing what you want with a trigger instead of a
rule?
regards, tom lane
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2003-06-22 20:28 Rules: passing new/old to functions Gunter Diehl <gdid@gmx.de>
2003-06-27 03:49 ` Tom Lane <tgl@sss.pgh.pa.us>
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