There was a discussion back here:
http://archives.postgresql.org/pgsql-bugs/2008-01/msg00189.php
that came to the conclusion that cross-type operators are a bad idea
if they don't come in complete sets: if you don't have an exact match
to the input types, and there are multiple possible candidates, then
the system doesn't know what to pick.
I looked through pg_operator just now, and found that we seem to be okay
as far as comparison operators go, but we do have issues for basic
arithmetic operators. Specifically, these cross-type operators aren't
part of complete sets:
OID | OPERATOR
548 | % (smallint,integer) 549 | % (integer,smallint)
690 | * (bigint,integer) 544 | * (smallint,integer) 694 | * (integer,bigint) 545 | * (integer,smallint)
688 | + (bigint,integer) 552 | + (smallint,integer) 692 | + (integer,bigint) 553 | + (integer,smallint)
689 | - (bigint,integer) 556 | - (smallint,integer) 693 | - (integer,bigint) 557 | - (integer,smallint)
691 | / (bigint,integer) 546 | / (smallint,integer) 695 | / (integer,bigint) 547 | / (integer,smallint)
We could either remove all of these, or fill in the sets. Removal
would mean that cross-type cases would get implemented as a coercion
function feeding a single-data-type operator, which would be marginally
slower to execute (I'm not sure it would be significant).
What I'm inclined to do is remove the two % operators, which don't seem
likely to be performance-critical, and fill in the missing int2-vs-int8
cases for the four basic arithmetic operators. But I could be talked
into just nuking everything listed above (and their underlying functions
of course).
Comments?
regards, tom lane
