Re: Minor difference in behavior between +/-

On Tuesday, January 24, 2023, Ryan Murphy <ryanmurf(at)gmail(dot)com> wrote:

> SELECT NULL - date '2023-01-05';
> -> result is null
> SELECT NULL + date '2023-01-05';
> -> result is [42725] ERROR: operator is not unique: unknown + date Hint:
> Could not choose a best candidate operator. You might need to add explicit
> type casts. Position: 13
>
>
There is no bug here.

> I would expect both of those to be null.
>

I get why you expect that but we expend little to no effort to handle null
in a type agnostic way. Type inference has to happen first and regardless
of whether the literal is null. Type inference failed in the + case but
not the - case. That is just happenstance of what operators happen to
exist in the system.

David J.