On 23 June 2016 at 18:31, Robert Haas <robertmh...@gmail.com> wrote:

>
> Sure, but aggregating as early as possible will often have the effect
> of dramatically reducing the number of tuples that have to pass
> through upper levels of the plan tree, which seems it would frequently
> far outweigh those considerations.
>

Agreed

I can imagine plans where a useful aggregation occurs before every join, so
N > 2 is easily possible.

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