Multiple worker thread will work together to do sequential scans, joins and aggregation. Some mentions here: http://rhaas.blogspot.com/2016/03/parallel-query-is

Multiple worker thread will work together to do sequential scans, joins and aggregation. Some mentions here: http://rhaas.blogspot.com/2016/03/parallel-query-is-getting-better-and.html http://rhaas.blogspot.com/2016/03/parallel-query-is-getting-... But this is just a start and there are lots more opportunities to improve as mentioned here: https://wiki.postgresql.org/wiki/Parallel_Query_Execution https://wiki.postgresql.org/wiki/Parallel_Query_Execution