Postgres NOT IN performance

Question

Any ideas how to speed up this query?

Input

EXPLAIN SELECT entityid FROM entity e

LEFT JOIN level1entity l1 ON l1.level1id = e.level1_level1id
LEFT         


        

Answer 1

ok my solution was

• select all entities
• left join all entities which have one of the ids (without the not is is faster) on the entityid
• select all rows where the joined select is NULL

as explained in

http://blog.hagander.net/archives/66-Speeding-up-NOT-IN.html