Re: NULL-handling in aggregate(DISTINCT ...)

>>>>> "Tom" == Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:

> Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk> writes:
>> Now the question: If the limit of one argument for DISTINCT aggs were
>> removed (which I'm considering doing as part of an update to the
>> aggregate ORDER BY patch I posted a while back), what should be the
>> behaviour of agg(distinct x,y) where one or both of x or y is null?
>> And should it depend on the strictness of the transition function?

Tom> I think you could probably just change it: make DISTINCT work as
Tom> per regular DISTINCT (treat null like a value, keep one copy).
Tom> All the spec-conforming aggregates are strict and would ignore
Tom> the null in the next step anyway.

Change it for single-arg DISTINCT too? And the resulting change to the
established behaviour of array_agg is acceptable? Just want to be clear
here.

--
Andrew.