Re:Fun with SQL: Window Functions in Postgres
by btilly on Monday June 04, 2018 @06:54PM
(#17233354)
That's another common variation, using a where in the outer query to select only a few of the rows from the window function.
And I've also used them as a better performing version of a full outer join - do a select of the combined fields from a window function query that is selected off of a UNION ALL. You have to jump a lot of hoops to do it, but the performance win can be worthwhile.
And I've also used them as a better performing version of a full outer join - do a select of the combined fields from a window function query that is selected off of a UNION ALL. You have to jump a lot of hoops to do it, but the performance win can be worthwhile.