In the new implementation of SampleLoader subclasses (used by order-by, skew-join ..) as part of the loader redesign, we are not only reading all the records input but also parsing them as pig tuples.
This is because the SampleLoaders are wrappers around the actual input loaders specified in the query. We can make things much faster by having a skipNext() function (or skipNext(int numSkip) ) which will avoid parsing the record into a pig tuple. LoadFunc could optionally implement this (easy to implement) function (which will be part of an interface) for improving speed of queries such as order-by. -Thejas
