Hello,
suppose you have two very simple tables with fk dependency, by which we join them
and another attribute for sorting
like this
select * from users join notifications on users.id=notifications.user_id ORDER BY users.priority desc ,notifications.priority desc limit 10;
Very typical web query.
No matter which composite indexes i try, postgresql can not make efficient nested loop plan using indexes.
It chooses all sorts of seq scans and hash joins or merge join and always a sort node and then a limit 10.
Neither plan provides acceptable performance. And tables tend to grow =\
Can anybody suggest something or explain this behavior?