Re: Domain breakage

This is now fixed in CVS, I believe by Tom's recent commit:

test=> create domain tint as int;
CREATE DOMAIN
test=> select 1::tint > (-1);
?column?
----------
t
(1 row)

test=> select 1::tint > (-1)::tint;
?column?
----------
t
(1 row)

---------------------------------------------------------------------------

Tom Lane wrote:
> Here's a fun one: in 7.3 or CVS tip, try
>
> regression=# create domain tint as int;
> CREATE DOMAIN
> regression=# select 1::tint > (-1);
> ?column?
> ----------
> t
> (1 row)
>
> regression=# select 1::tint > (-1)::tint;
> ?column?
> ----------
> f
> (1 row)
>
> How's that again? Well, when you dig into it you find that the second
> case is invoking the OID greater-than operator (oidgt), which does
> unsigned comparison. Why is it picking oidgt and not int4gt,
> considering that the domain is based on int4? Well, the problem is that
> the domain type is considered binary-compatible with both int4 and oid;
> there isn't any stronger connection to the base type than there is to
> any other type that's binary-compatible with the domain. So
> oper_select_candidate gets down to its third tiebreaker, preferred-type
> status ... and guess what, OID is a preferred type in its category while
> int4 is not preferred in its category.
>
> I suspect that the most workable fix for this is to reduce all the input
> typeids to base types before we start the operator or function type
> resolution routines. However, this would completely destroy any hope of
> making domain-specific operators.
>
> (I'm also reminded once again that I don't like the preferred-type
> heuristics. They're too likely to produce surprising choices.)
>
> A different line of attack would be to modify the operator/function
> resolution rules to take account of domain relationships explicitly,
> making the binding of domain to base type stronger than mere binary
> equivalence. But I'm not clear how that might work.
>
> Any ideas?
>
> regards, tom lane
>
>
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