Re: Final Patch for GROUPING SETS

On Mon, Dec 22, 2014 at 10:46:16AM -0500, Tom Lane wrote:
> I still find the ChainAggregate approach too ugly at a system structural
> level to accept, regardless of Noah's argument about number of I/O cycles
> consumed.  We'll be paying for that in complexity and bugs into the
> indefinite future, and I wonder if it isn't going to foreclose some other
> "performance opportunities" as well.

Among GROUPING SETS GroupAggregate implementations, I bet there's a nonempty
intersection between those having maintainable design and those having optimal
I/O usage, optimal memory usage, and optimal number of sorts.  Let's put more
effort into finding it.  I'm hearing that the shared tuplestore is
ChainAggregate's principal threat to system structure; is that right?