org.apache.hadoop.hive.ql.optimizer.correlation
Class ReduceSinkDeDuplication

java.lang.Object
  org.apache.hadoop.hive.ql.optimizer.correlation.ReduceSinkDeDuplication

All Implemented Interfaces:

Transform

public class ReduceSinkDeDuplication
extends Object
implements Transform

If two reducer sink operators share the same partition/sort columns and order, they can be merged. This should happen after map join optimization because map join optimization will remove reduce sink operators. This optimizer removes/replaces child-RS (not parent) which is safer way for DefaultGraphWalker.

Nested Class Summary

static class

ReduceSinkDeDuplication.AbsctractReducerReducerProc

Constructor Summary

ReduceSinkDeDuplication()

Method Summary

ParseContext

transform(ParseContext pctx) All transformation steps implement this interface.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ReduceSinkDeDuplication

public ReduceSinkDeDuplication()

Method Detail

transform

public ParseContext transform(ParseContext pctx)
                       throws SemanticException

Description copied from interface: Transform

All transformation steps implement this interface.

Specified by:

transform in interface Transform

Parameters:

pctx - input parse context

Returns:

ParseContext

Throws:

SemanticException