How do I create named window partitions (aliases) in PostgreSQL?

Question

The documentation for PostgreSQL window functions seems to imply you can use the same named window in multiple places in your query. However, I can't figure out how do I create a named window?

SELECT first_value(vin) OVER( PARTITION BY vin ) AS w, first_value(make) OVER w
FROM inventory.vehicles
WHERE lot_Id = 9999 AND make is not null;

This is a joke query I'm trying to get the syntax to take, but I'm getting error:

ERROR: window "w" does not exist

Answer 1

The answer was actually in the SELECT doc:

WINDOW Clause

The optional WINDOW clause has the general form

WINDOW window_name AS ( window_definition ) [, ...]

Here is an example,

SELECT first_value(vin) OVER w,
  first_value(make) OVER w
FROM inventory.vehicles
WHERE lot_Id = 9999
  AND make is not null
WINDOW w AS ( PARTITION by vin );