where does the JOIN happen when SELECT statement was executed thru DBLink?

Hi all,

My questions as titled.

For example,

1) select XXXX from TBL_A inner join TBL_B@dblink on TBL_A.id = TBL_B.id;

2) select XXXX from TBL_A@dblink inner join TBL_B@dblink on TBL_A.id = TBL_B.id;

According to my test result(thru explain plan), I see the JOIN happens in local site in 1), and in remote site in 2).

But there are no documents mention on this, so I have no idea whether it is the default behavior,

or it is decided by the optimizer.

Any advices are appreciated.

Regards.