On Jun 22, 2006, at 1:09 PM, Tom Lane wrote:
Lukas Smith <[EMAIL PROTECTED]> writes:
Jochem van Dieten wrote:
make the session handler smarter? And if you can't do that, put some
logic in the session table that turns an update without changes into a

err isnt that one the job of the database?

No.  That idea has been suggested and rejected before.  Detecting that
an UPDATE is a no-op would require a significant number of cycles, and
in most applications, most or all of the time those cycles would be
wasted effort.  If you have a need for this behavior, you can attach a
BEFORE UPDATE trigger to a table that checks for all-fields-the- same and
suppresses the update.  I don't think that should be automatic though.

What would be nice to add is the ability to perform that check more easily. As of 8.1...

create function test() returns trigger as $$
if NEW=OLD then
return null;
return NEW;
end if;
create trigger test before update on test execute procedure test();
update test set i=i;
ERROR:  operator does not exist: test = test
HINT: No operator matches the given name and argument type(s). You may need to add explicit type casts.
CONTEXT:  SQL statement "SELECT   $1 = $2 "
PL/pgSQL function "test" line 2 at if
Jim C. Nasby, Sr. Engineering Consultant      [EMAIL PROTECTED]
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461

---------------------------(end of broadcast)---------------------------
TIP 2: Don't 'kill -9' the postmaster

Reply via email to