I wrote:
> jian he <jian(dot)universality(at)gmail(dot)com> writes:
>> within ATExecAddColumn, we can
>> if (!missingIsNull)
>> StoreAttrMissingVal(rel, attribute->attnum, missingval, missingIsNull);
>> to save some cycles?
> Probably not really worth it: surely that's going to be a very
> infrequent edge case.
On second thought, it is worth doing like that, not on speed
grounds but because we can make StoreAttrMissingVal simpler
by not handling the is-null case at all.
Pushed with that adjustment and some other minor polishing.
regards, tom lane