Re: Delete tables difference involves seq scan

2017-12-01 Thread Danylo Hlynskyi
I was able to speedup original query a lot by using CTE. It still uses seq scan on `diff` table, but looks like it does this once: explain with diff as (select id from drug_refills_diff) delete from drug_refills where id in (select id from diff); Q

Re: Delete tables difference involves seq scan

2017-12-01 Thread Danylo Hlynskyi
Oh, sorry, this happens on Postgresql 9.6.6. I've checked that on Postgresql 10.0 query plan from setup (1) now uses two seq scans, like in setup (2). 2017-12-01 15:03 GMT+02:00 Danylo Hlynskyi : > Hello. I want to remove rows from first table, that exist in second > (equality is done using PK).

Delete tables difference involves seq scan

2017-12-01 Thread Danylo Hlynskyi
Hello. I want to remove rows from first table, that exist in second (equality is done using PK). However I experience seq scan on second table, which counters my intuition - I think it should be index-only. Because tables are large, performance of query is very bad. However I got mixed results whe