[HACKERS] Aggregation push down, reorder of join and group by

Hello, I'm reading some papers about aggregation push down like in " https://ub-madoc.bib.uni-mannheim.de/37228/1/main.pdf"; and " http://www.vldb.org/conf/1995/P345.PDF";. I think it is very useful but very complex to implement. In some complex queries, it can be a lot faster. Is there any plan t

[HACKERS] Cardinality estimation for group by

Friends, How is cardinality estimation for "group by" is done and where is the code doing that? Best Regards, Chenxi Li