SQL generation in Framework Manager

[jeeva]

Hi,

we are connecting 2 databases of Progress openedge 11 at a time using single odbc DSN in Framework manager. when we are testing the querysubjects in framework manager, it displaying the native sql using joins.
if we dont use single odbc dsn, FM displaying the native sql without any joins.

i am assuming progress database itself applying all joins and giving data to cognos, so because of this reason it improve the performance.
is it correct ?
please share your thoughts.

thanks.