On 18 March 2016 at 10:13, James Sewell <james.sew...@lisasoft.com> wrote: > This does bring up an interesting point I don't quite understand though. If I > run parallel agg on a table with 4 rows with 2 workers will it run on two > workers (2 rows each) or will the first one grab all 4 rows? It works on a per page basis, workers just each grab the next page to be scanned from a page counter that sits in shared memory, the worker just increments the page number, releases the lock on the counter and scans that page.
See heap_parallelscan_nextpage() So the answer to your question is probably no. At least not unless the the page only contained 2 rows. -- David Rowley http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
