Re: NULL and plpgsql rows

On Oct 2, 2006, at 6:28 PM, Tom Lane wrote:
> "Jim C. Nasby" <jim(at)nasby(dot)net> writes:
>> However, the test right above that means that we'll fail if the user
>> tries something like "row_variable := NULL;":
>
> The patch you seem to have in mind would allow
> row_variable := int_variable;
> to succeed if the int_variable chanced to contain NULL, which is
> surely
> not very desirable.

Hrm... is there any reasonable way to catch that?

> The real issue here is that the bare NULL has type UNKNOWN and
> we're not
> making any effort to cast it. I'm not sure whether it'd work to
> simply
> apply exec_cast_value --- that looks like it's only meant to handle
> scalars, where in general you'd need something close to
> ExecEvalConvertRowtype().
>
>> Of course, setting a row variable to null is a lot more useful if
>> we can
>> actually test for it after the fact, and I'm not really sure how
>> to make
>> that happen.
>
> Doesn't IS NULL work (as of CVS HEAD)?

Ahh, so it does. Doesn't work with RECORD, though... which seems a
bit surprising. I can't really think of a good reason why they should
differ.

ERROR: record "v_row" is not assigned yet
DETAIL: The tuple structure of a not-yet-assigned record is
indeterminate.
CONTEXT: PL/pgSQL function "test" line 4 at return

--
Jim Nasby jim(at)nasby(dot)net
EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)