On Mon, Oct 13, 2008 at 09:10:41PM -0400, Tom Lane wrote: > Eric Haszlakiewicz <erh@xxxxxxxxxxxxxx> writes: > > I created this, which seems to solve the problem: > > > create function casting_eq_operator(integer, "char") > > returns boolean as 'begin > > return $1 = cast ($2 as integer); > > end;' language plpgsql immutable strict; > > > CREATE OPERATOR = (PROCEDURE = casting_eq_operator, > > LEFTARG = integer , RIGHTARG = "char", > > COMMUTATOR = =, NEGATOR = !=, HASHES, MERGES > > ); > > > Can this be included by default? > > No. Even if we desired to reverse the decision about not having > implicit casting behavior, this definition of the operator would not be > appropriate because it provides the opposite of the old behavior. > The pre-8.3 behavior would have been to cast the integer to text and > apply a textual comparison; which gives different comparison behavior, > eg leading zeroes in the string would affect the result. Not to mention > that the cast to integer in this definition would fail outright if the > string didn't look like an integer. > > A large part of the reasoning for getting rid of the implicit casts > was exactly that it's not very clear what a comparison of this sort > should act like, and most people who are accidentally invoking it > haven't thought that through either. hmm.. I was thinking that a comparison between a number and a string would cause an error if the string wasn't parseable. Now that I think about it more, I can see that having it just return false might be reasonable too. > > (Some other problems: I'm pretty sure you meant to refer to text or > varchar not "char"; you referenced commutator and negator operators > without defining them; this operator certainly does not hash, and > I don't think it merges either, though maybe you could make the latter > work if you'd provided all the requisite btree-opfamily infrastructure.) Yeah, you're right. I didn't think that through entirely. Sorry for the noise. eric -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
