Re: [HACKERS] merging some features from plpgsql2 project

On 1/9/17 5:53 PM, Marko Tiikkaja wrote:

        My idea was that the currently unsupported combination of NOT
        NULL and
        no DEFAULT would mean "has to be assigned to a non-NULL value
        before it
        can be read from, or an exception is thrown".  Solves the most
        common
        use case and is backwards compatible.


    That won't allow you to use a variable in multiple places though...
    is there a reason we couldn't support something like IS DEFINED and
    UNSET?


I don't understand what your use case is.  Could you demonstrate that
with some code you'd write if these features were in?

One use case is NEW and OLD in triggers. Checking to see if one or the other is set is easier than checking TG_OP. It's also going to be faster (probably MUCH faster; IIRC the comparison currently happens via SPI).

Another case is selecting into a record:

EXECUTE ... INTO rec;
IF rec IS DEFINED THEN
ELSE
  EXECUTE <something else> INTO rec;
  IF rec IS DEFINED THEN