OLD pseudo relation for INSERT in rules and triggers - Mailing list pgsql-general

From Rafał Pietrak
Subject OLD pseudo relation for INSERT in rules and triggers
Date
Msg-id 50E3283C.9090207@zorro.isa-geek.com
Whole thread Raw
Responses Re: OLD pseudo relation for INSERT in rules and triggers
List pgsql-general
Hello the list,

As far as I can tell from a quick search through postgresql documentation, the OLD.* pseudorelation is not available for INSERT triggers and rules. And a little googleing I did, haven't pointed me to anything relevant to the following. My apology if I miss in my search such discussion happening earlier (I apreciate a pointer, where I can see pros and cons that've been raisen back then);

If not, I think having OLD.* in INSERT rules/triggers is worth pondering.

The thing is, that it would be a valuable tool to mimic table-propper functionality by a view. The OLD.* preudorelation on INSERT could provide column defaults from the underlaying table definition.

like:
 CREATE TABLE test (tm timestamp default now(), info text);
 CREATE TABLE test_view AS SELECT * FROM test;
 CREATE RULE with_defaults AS ON INSERT to test_view DO INSTEAD INSERT INTO test (tm,info) VALUES ( COALESCE(NEW.tm, OLD.tm), NEW.text);

so:
 INSERT INTO test_view (info) VALUES ('hello');
and:
 INSERT INTO test_view (tm, info) VALUES (null, 'hello');

both work just as if test_view was a TABLE with a default tm value defined.

-R

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