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.


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

Simon Riggs                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Reply via email to