On 11th of February, Tom Lane committed patch: Remove GROUP BY columns that are functionally dependent on other columns. If a GROUP BY clause includes all columns of a non-deferred primary key, as well as other columns of the same relation, those other ...

On 16th of May, Andres Freund committed patch: Support GROUPING SETS, CUBE and ROLLUP. This SQL standard functionality allows to aggregate data by different GROUP BY clauses at once. Each grouping set returns rows with columns grouped by in other sets set to NULL. This ...

On 12th of December, Tom Lane committed patch: Improve EXPLAIN to print the grouping columns in Agg and Group nodes. Per request from Kevin Grittner.