Does Oracle Partition by Reference optimizes join queries Oracle 11g has a new feature in partitioning tables called partition by reference.

I want to know whether Oracle joins (nested-loop-joins or hash-join or ...) rows from proper partitions when joining two tables or now?

How can one be sured of that?
I think the answer to your question is "Yes".

The Oracle optimizer understands reference partitioning. See the Oracle documentation at http://docs.oracle.com/cd/E11882_01/server.112/e25523/part_avail.htm#BJECHCAG

Also see http://www.orafaq.com/node/2591