2009/3/6 Christian Schröder <cs@xxxxxxxxx>
Hi list,
if I want to find all records from a table that don't have a matching record in another table there are at least two ways to do it: Using a left outer join or using a subselect. I always thought that the planner would create identical plans for both approaches, but actually they are quite different which leads to a bad performance in one case.
Couldn't you also use: SELECT fk FROM b EXCEPT SELECT id FROM a;
