"SELECT SINGLE" vs. "SELECT UP TO 1 ROWS"

Hello everyone,

I've spend the last 2 hours comparing and researching the above mentioned statements and I don't have a clear result.

Is there any official documentation which statement should process a SELECT faster that I expect to return only one record as a result of accessing only non-(unique-)index fields?

Does this also depend on the used DBMS (ORACLE 10.2.0.4.0) and/or the SAP release (NW 7.01 SP6)?

Would be great to get some feedback from the performance gurus!

Thanks in advance and best regards,

Alej