Обсуждение: Cast has higher precedence than -

Given this domain...
CREATE DOMAIN loan.loan_amount numeric(7,2) --loan.loan_amount_rawCONSTRAINT loan_amount__greater_equal_0 CHECK( VALUE
>=0 )CONSTRAINT loan_amount__less_equal_20000 CHECK( VALUE <= 20000 )
 
;

I was rather surprised by

select -1::loan.loan_amount; ?column?
----------    -1.00
(1 row)

The problem is that :: binds more tightly than -:

select (-1)::loan.loan_amount;
ERROR:  value for domain loan.loan_amount violates check constraint 
"loan_amount__greater_equal_0"

Is this by design? If not, any ideas how bad it'd be to fix?
-- 
Jim Nasby, Data Architect, Blue Treble Consulting
Data in Trouble? Get it in Treble! http://BlueTreble.com

Jim Nasby <Jim.Nasby@BlueTreble.com> writes:
> The problem is that :: binds more tightly than -

This is well known, and even well documented.

> Is this by design? If not, any ideas how bad it'd be to fix?

It is by design.  The core argument for doing it is that '-' might have
type-dependent semantics that would not be reproduced by negating first
and casting afterwards.

Even if you could convince people that that concern is baseless, there
would be a backwards-compatibility problem.  For a comparison point,
note the hurdles I had to jump to persuade people that we should change
the precedence of comparison operators --- something that has clear
support in the standard, as this change would not.
        regards, tom lane