Re: Trouble with hashagg spill I/O pattern and costing

On Thu, 2020-05-21 at 20:54 +0200, Tomas Vondra wrote:
> The last column is master with the tlist tweak alone - it's better
> than
> hashagg on master alone, but it's not nearly as good as with both
> tlist
> and prealloc patches.

Right, I certainly think we should do the prealloc change, as well.

I'm tweaking the patch to be a bit more flexible. I'm thinking we
should start the preallocation list size ~8 and then double it up to
~128 (depending on your results). That would reduce the waste in case
we have a large number of small partitions.

Regards,
	Jeff Davis