Re: asynchronous and vectorized execution

Hello,

I considered applying the async infrastructure onto nodeGather,
but since parallel workers hardly make Gather (or the leader)
wait, it's really useless at least for simple cases. Furthermore,
as several people may have said before, being defferent from
foreign scans, gather (or other kinds of parallel) nodes usually
have several workers and will have up to two digit nubmers at the
most even on so-called many-core boxes. I finally gave up
applying this to nodeGather.

As the result, the attached patchset is functionally the same
with the last version but replace misused Assert with
AssertMacro.

regards,

-- 
Kyotaro Horiguchi
NTT Open Source Software Center