Jung, Jinho schrieb am 28.02.2021 um 16:04: > # Performance issues discovered from differential test > > For example, the below query runs x1000 slower than other DBMSs from > PostgreSQL. > > select ref_0.ol_amount as c0 > from order_line as ref_0 > left join stock as ref_1 > on (ref_0.ol_o_id = ref_1.s_w_id ) > inner join warehouse as ref_2 > on (ref_1.s_dist_09 is NULL) > where ref_2.w_tax is NULL;
I find this query extremely weird to be honest. There is no join condition between warehouse and the other two tables which results in a cross join. Which is "reduced" somehow by applying the IS NULL conditions - but still, to me this makes no sense. Maybe the Postgres optimizer doesn't handle this ugly "join condition" the same way the others do. I would rather expect a NOT EXISTS against the warehouse table. Thomas
