Re: Questions regarding distinct operation implementation

We do our best to ensure that a given executor node never uses more
than work_mem.  Certainly, we still do have nodes that can exceed this
by a long way.  It would be unlikely that we'd accept anything new
that could do this.  

Makes sense, also would definitely rule out any brute force algorithms. Good point to know

providing you can code it in such a way that you only
allocate one of these at once, i.e not allocate one per DISTINCT
aggregate all at once.

I am not sure if I understand this, does it means at given time, do allocation for only one distinct aggregate
instead of all, in case of multiple aggregates using distinct? 

-- 
Regards,
Ankit Kumar Pandey