Hinting to Redshift how to distribute a join? If I am joining between two tables, A and B, with multiple equality constraints, is there any way that I can hint to Redshift which it should use for distributing the join? For example, in:

FROM A
JOIN B
  ON  B.id = A.b_id
  AND B.x = some_expression_of(A.x)


In my situation, I know that all the data is already distributed by this X expression, so that if Redshift distributes by it, there will not be any actual network activity.



Edit: Here's a more representative version of the join:

FROM order_products --distribution key: user_id
FULL OUTER JOIN order_payments --distribution key: user_id
   ON FALSE
LEFT JOIN orders --distribution key: user_id
   ON  orders.id = COALESCE(order_products.order_id, order_payments.order_id)
   AND orders.user_id = COALESCE(order_products.user_id, order_payments.user_id)


What I'd like is to just be able to tell Redshift to please distribute the last join based on user_id (which Redshift might categorize as a  DS_DIST_BOTH, but should actually result in no network redistribution)
You cannot use hints in Redshift like Oracle. You can do things like set the distribution keys. If X is always used in that fashion, it may make sense to incorporate that into your DDL.  

See here:
http://docs.aws.amazon.com/redshift/latest/dg/t_Distributing_data.html