Joint Query - Involving tables from tablespaces of different Block Sizes

There was a discussion about the behaviour of SQL queries involving more than one tablespaces of different blocksizes.

We know, there are different data buffer cache areas in SGA for each of the non-default blocksize tablespaces. So the data fetched from different tablespaces are loaded into their corresponding buffer caches.

Does the Join query has any influence on this? i.e. Because we require different columns from
different size tablespaces, do all the data get loaded in only the default buffer cache?
Ans. is NO - because row data are staged in the buffer caches only to be further processed elsewhere?
i.e.SQL Work Area of PGA's Private SQL Area
(needs more update...)