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.
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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
