Re: Convert planner's AggInfo and AggTransInfo to Nodes

I wrote:
> * WRITE_OID_ARRAY and WRITE_BOOL_ARRAY needed extension to handle a null
> array pointer. I think we should make all the WRITE_FOO_ARRAY macros
> work alike, so I added that to all of them. I first tried to make the
> rest work like WRITE_INDEX_ARRAY, but that failed because readfuncs.c
> isn't expecting "<>" for an empty array; it's expecting nothing at
> all. (Note there is no readfuncs equivalent to WRITE_INDEX_ARRAY.)
> What I've done here is to change WRITE_INDEX_ARRAY to work like the
> others and print nothing for an empty array, but I wonder if now
> wouldn't be a good time to redefine the serialized representation
> to be more robust. I'm imagining "<>" for a NULL array pointer and
> "(item item item)" otherwise, allowing a cross-check that we're
> getting the right number of items.

Concretely, about like this.

regards, tom lane