This change significantly simplifies query executor code. Before this
change there were two types of executors -- RawExecutor and
AggregateExecutor. These two types only differed in one function
Execute(). Otherwise all other methods on the Executors were common and
duplicated between executors
This change merges the two executors into a single type called, wait for
it, Executor and simply switches execute functions depending on the
statement type.
Ben Johnson
Philip O'Toole
Philip O'Toole