(1) On a federated database, a means of processing a query fragment if the data source cannot process the fragment or if the federated database can process the fragment faster than the data source can. See also push-down processing, query optimizer.
(2) The means by which operations in a process that have successfully completed can be undone if an error occurs, to return the system to a consistent state.
(3) The action that a collaboration takes during rollback of a transaction to undo a previously executed service call. Such an action semantically negates the action taken by a corresponding step in the service call, which has already been executed. For example, the compensation step for a Create action might involve deleting the object just created. See also isolation checking, minimum transaction level, transactional collaboration.