If quickpass mode can be used, Component Integration Services produces a simplified query plan in which the entire statement is pushed to a remote server.
If quickpass mode cannot be used, the Adaptive Server optimizer generates a plan for executing the entire statement. This plan is then examined and portions of the plan are chosen to be pushed off to remote servers. As much of the original plan is pushed off as is possible based on the locations of the tables and the capabilities of the remote servers. The remote statement may come very close to the original statement for a fully capable remote server. A more minimal statement may be produced for other servers with the local Adaptive Server executing the portion of the plan that could not be sent.
For example, if a client entered the statement:
select a,b from table1 where cos(a) > 0 and sin(b) > 0
If the remote server that owned table1 supported cos() but not sin(), the statement sent to the remote server would be:
select a,b from table1 where cos(a) > 0
The local server would then have a plan that would apply the check for sin(b) > 0 to the result set returned by the remote server.
