| From: | Rafał Pietrak <rafal(at)zorro(dot)isa-geek(dot)com> | 
|---|---|
| To: | pgsql-general(at)postgresql(dot)org | 
| Subject: | OLD pseudo relation for INSERT in rules and triggers | 
| Date: | 2013-01-01 18:17:32 | 
| Message-ID: | 50E3283C.9090207@zorro.isa-geek.com | 
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| Thread: | |
| Lists: | 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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