1. One or more computer-readable media comprising computer-executable instructions for optimizing a performance of a data processing job, the computer-executable instructions directed to steps comprising: selecting a first set of operations to carry out the data processing job; augmenting at least some operations, of the first set of operations, to comprise computer-executable instructions for collecting execution statistics quantifying execution of the augmented operations; receiving at least some of the execution statistics prior to the data processing job having been completed; selecting, based on the received execution statistics, a second set of operations that are semantically equivalent to the first set of operations; and proceeding with the data processing job with the second set of operations.