org.apache.hadoop.hive.ql.optimizer

Class GenMRUnion1

java.lang.Object

org.apache.hadoop.hive.ql.optimizer.GenMRUnion1

All Implemented Interfaces:

NodeProcessor

public class GenMRUnion1
extends java.lang.Object
implements NodeProcessor

Processor for the rule - TableScan followed by Union.

Constructor Summary

Constructors

Constructor and Description
GenMRUnion1()

Method Summary

Modifier and Type	Method and Description
java.lang.Object	process(Node nd, java.util.Stack<Node> stack, NodeProcessorCtx opProcCtx, java.lang.Object... nodeOutputs) Union Operator encountered .

Methods inherited from class java.lang.Object

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

Constructor Detail

GenMRUnion1

public GenMRUnion1()

Method Detail

process

public java.lang.Object process(Node nd,
                                java.util.Stack<Node> stack,
                                NodeProcessorCtx opProcCtx,
                                java.lang.Object... nodeOutputs)
                         throws SemanticException

Union Operator encountered . Currently, the algorithm is pretty simple: If all the sub-queries are map-only, don't do anything. Otherwise, insert a FileSink on top of all the sub-queries. This can be optimized later on.

Specified by:

process in interface NodeProcessor

Parameters:

nd - the file sink operator encountered

opProcCtx - context

nodeOutputs - A variable argument list of outputs from other nodes in the walk

Returns:

Object to be returned by the process call

Throws:

SemanticException