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

Class QueryPlanTreeTransformation

java.lang.Object

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

public class QueryPlanTreeTransformation
extends Object

QueryPlanTreeTransformation contains static methods used to transform the query plan tree (operator tree) based on the correlation we have detected by Correlation Optimizer.

Constructor Summary

Constructors

Constructor and Description
QueryPlanTreeTransformation()

Method Summary

Methods

Modifier and Type	Method and Description
protected static void	applyCorrelation(ParseContext pCtx, CorrelationOptimizer.CorrelationNodeProcCtx corrCtx, IntraQueryCorrelation correlation) Based on the correlation, we transform the query plan tree (operator tree).

Methods inherited from class java.lang.Object

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

Constructor Detail

QueryPlanTreeTransformation

public QueryPlanTreeTransformation()

Method Detail

applyCorrelation

protected static void applyCorrelation(ParseContext pCtx,
                    CorrelationOptimizer.CorrelationNodeProcCtx corrCtx,
                    IntraQueryCorrelation correlation)
                                throws SemanticException

Based on the correlation, we transform the query plan tree (operator tree). In here, we first create DemuxOperator and all bottom ReduceSinkOperators (bottom means near TableScanOperaotr) in the correlation will be be the parents of the DemuxOperaotr. We also reassign tags to those ReduceSinkOperators. Then, we use MuxOperators to replace ReduceSinkOperators which are not bottom ones in this correlation. Example: The original operator tree is ... JOIN2 / \ RS4 RS5 / \ GBY1 JOIN1 | / \ RS1 RS2 RS3 If GBY1, JOIN1, and JOIN2 can be executed in the same reducer (optimized by Correlation Optimizer). The new operator tree will be ... JOIN2 | MUX / \ GBY1 JOIN1 \ / DEMUX / | \ / | \ / | \ RS1 RS2 RS3

Parameters:

pCtx -

corrCtx -

correlation -

Throws:

SemanticException