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 Object
- implements NodeProcessor
Processor for the rule - any operator tree followed by union
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
GenMRUnion1
public GenMRUnion1()
process
public Object process(Node nd,
Stack<Node> stack,
NodeProcessorCtx opProcCtx,
Object... nodeOutputs)
throws SemanticException
- Union Operator encountered .
Currently, the algorithm is pretty simple:
If all the sub-queries are map-only, dont 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 encounteredopProcCtx
- contextnodeOutputs
- A variable argument list of outputs from other nodes in the walk
- Returns:
- Object to be returned by the process call
- Throws:
SemanticException
Copyright © 2009 The Apache Software Foundation