Robert Haas wrote:
On Wed, Sep 2, 2009 at 9:52 PM, Itagaki
Takahiro<itagaki.takah...@oss.ntt.co.jp> wrote:
Here is a patch to implement "Support triggers on columns" in our ToDo list.
The syntax is:
CREATE TRIGGER name
BEFORE UPDATE OF col1, col12, ...
ON tbl FOR EACH ROW EXECUTE PROCEDURE func();
I consulted the previous work following:
Column-level triggers (From: Greg Sabino Mullane, Date: 2005-07-04)
http://archives.postgresql.org/pgsql-patches/2005-07/msg00107.php
and completed some under-construction parts.
It's still arguable that we should add dependencies from column
triggers to referenced columns. In the present patch, dropeed
columns are just ignored and always considered as not-modified.
Please grep with "TODO: (TRIGGER)" to check the issue.
Comments welcome.
Wow, so I wouldn't have to do this any more?
IF (TG_OP = 'UPDATE') THEN
IF (OLD.foo IS NOT DISTINCT FROM NEW.foo AND OLD.bar IS NOT
DISTINCT FROM NEW.bar
AND OLD.baz IS NOT DISTINCT FROM NEW.baz) THEN
RETURN NULL;
END IF;
END IF;
Apart from any possible gain in efficiency, the sheer savings in
typing sound quite awesome.
You could make it nicer with something like:
row(new.foo,new.bar,new.baz) is distinct from
row(old.foo,old.bar,old.baz)
couldn't you?
I'm actually having trouble thinking of a case where I'd find this
feature very useful.
cheers
andrew
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