Hey All, I've been doing some (futile) work trying to speed up aggregates with a group by in PostgreSQL 9.5.
I installed PostgreSQL 9.6 on the same machine to see if I could get anything running in parallel when using partitioning - which didn't work. But - I did find this: With the following setup: CREATE TABLE base( view_time TIMESTAMP WITHOUT time ZONE, view_time_day TIMESTAMP WITHOUT time ZONE, count_n numeric); INSERT INTO base SELECT view_time, date_trunc('day', view_time), COUNT::numeric, FROM (SELECT TIMESTAMP '2015-12-01' + random() * interval '30 days' AS view_time, trunc(random() * 99 + 1) AS COUNT FROM generate_series(1,30000000)) a; analyze base; Now when I run the following SQL (multiple times to allow for getting everything into shared buffers, which is 4GB on my machine): select sum(count_n) from base group by view_time_day; I get the following results: PSQL 9.5 - *~21 seconds* PSQL 9.6 devel - *~8.5 seconds* I think that's pretty good! I know this is a devel release, things may change, blah blah. But still, something has changed for the better here! I get the same plan on both nodes: HashAggregate (cost=670590.56..670590.95 rows=31 width=13) Group Key: view_time_day -> Seq Scan on base (cost=0.00..520590.04 rows=30000104 width=13) Cheers, James Sewell, PostgreSQL Team Lead / Solutions Architect ______________________________________ Level 2, 50 Queen St, Melbourne VIC 3000 *P *(+61) 3 8370 8000 *W* www.lisasoft.com *F *(+61) 3 8370 8099 -- ------------------------------ The contents of this email are confidential and may be subject to legal or professional privilege and copyright. No representation is made that this email is free of viruses or other defects. If you have received this communication in error, you may not copy or distribute any part of it or otherwise disclose its contents to anyone. Please advise the sender of your incorrect receipt of this correspondence.