Passthrough mode is provided within Component Integration Services as a means of enabling a user to perform native operations on the server to which the user is being “passed through.”
For example, requesting passthrough mode for an Oracle server, allows you to send native Oracle SQL statements to the Oracle DBMS. Results are converted into a form that is usable by the Open Client™ application and passed back to the user.
The Transact-SQL® parser and compiler are bypassed in this mode, and each language batch received from the user is passed directly to the server to which the user is connected in passthrough mode. Results from each batch are returned to the client.
There are several ways to use passthrough mode:
The connect to command
The sp_autoconnect stored procedure
The sp_passthru stored procedure
The sp_remotesql stored procedure