Parallel execution and RAC

Hi All,

My DB is 11.1 and I have 2 nodes 1 and 2 in my rac.

In the batch processing, most of SQLs are executed in parallel (parallel query and parallel DML). Does my following assumption make sense or not?

Parallel execution reads data blocks into PGA instead of SGA. So cache fusion of RAC won't help for parallelized SQL.

And if the slave sesseions can't be distributed evenly across node1 and 2, it will have no obvious benefit over the single instance?

In reality, I find that most slave sessions are populated in node1 and just the coresponding qc sessions are in node2. (I queried dba_hist_active_sess to get this information)