org.apache.hadoop.hive.ql.optimizer

Class BucketingSortingReduceSinkOptimizer

java.lang.Object

org.apache.hadoop.hive.ql.optimizer.BucketingSortingReduceSinkOptimizer

All Implemented Interfaces:

Transform

public class BucketingSortingReduceSinkOptimizer
extends java.lang.Object
implements Transform

This transformation does optimization for enforcing bucketing and sorting. For a query of the form: insert overwrite table T1 select * from T2; where T1 and T2 are bucketized/sorted on the same keys, we don't need a reducer to enforce bucketing and sorting. It also optimizes queries of the form: insert overwrite table T1 select * from T1 join T2 on T1.key = T2.key where T1, T2 and T3 are bucketized/sorted on the same key 'key', we don't need a reducer to enforce bucketing and sorting

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	BucketingSortingReduceSinkOptimizer.BucketSortReduceSinkProcessor BucketSortReduceSinkProcessor.

Constructor Summary

Constructors

Constructor and Description
BucketingSortingReduceSinkOptimizer()

Method Summary

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

Methods inherited from class java.lang.Object

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

Constructor Detail

BucketingSortingReduceSinkOptimizer

public BucketingSortingReduceSinkOptimizer()

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