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

Class ReduceSinkDeDuplication

java.lang.Object

org.apache.hadoop.hive.ql.optimizer.Transform

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

public class ReduceSinkDeDuplication
extends 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

Nested Classes

Modifier and Type	Class and Description
static class	ReduceSinkDeDuplication.AbsctractReducerReducerProc
protected class	ReduceSinkDeDuplication.ReduceSinkDeduplicateProcCtx

Field Summary

Fields

Modifier and Type	Field and Description
protected static org.slf4j.Logger	LOG
protected ParseContext	pGraphContext

Constructor Summary

Constructors

Constructor and Description
ReduceSinkDeDuplication()

Method Summary

Modifier and Type	Method and Description
ParseContext	transform(ParseContext pctx) All transformation steps implement this interface.

Methods inherited from class org.apache.hadoop.hive.ql.optimizer.Transform

beginPerfLogging, endPerfLogging, endPerfLogging

Methods inherited from class java.lang.Object

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

Field Detail

LOG

protected static final org.slf4j.Logger LOG

pGraphContext

protected ParseContext pGraphContext

Constructor Detail

ReduceSinkDeDuplication

public ReduceSinkDeDuplication()

Method Detail

transform

public ParseContext transform(ParseContext pctx)
                       throws SemanticException

Description copied from class: Transform

All transformation steps implement this interface.

Specified by:

transform in class Transform

Parameters:

pctx - input parse context

Returns:

ParseContext

Throws:

SemanticException