On 06/20/2018 10:12 PM, Heikki Linnakangas wrote: > Currently, the planner always first decides the scan/join order, and > adds Group/Agg nodes on top of the joins. Sometimes it would be legal, > and beneficial, to perform the aggregation below a join. I've been > hacking on a patch to allow that. >
There was a patch [1] from Antonin Houska aiming to achieve something similar. IIRC it aimed to push the aggregate down in more cases, leveraging the partial aggregation stuff. I suppose your patch only aims to do the pushdown when the two-phase aggregation is not needed? [1] https://www.postgresql.org/message-id/flat/9666.1491295317@localhost regards -- Tomas Vondra http://www.2ndQuadrant.com PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
