Package org.apache.vxquery.compiler.rewriter.rules

Class ConvertAssignToUnnestRule

java.lang.Object

org.apache.vxquery.compiler.rewriter.rules.AbstractUsedVariablesProcessingRule

org.apache.vxquery.compiler.rewriter.rules.ConvertAssignToUnnestRule

All Implemented Interfaces:

org.apache.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule

public class ConvertAssignToUnnestRule
extends AbstractUsedVariablesProcessingRule

The rule searches for unnest(iterate) operator followed by an assign(child) operator and merges the assign into the unnest operator.

 Before
 
   plan__parent
   UNNEST( $v2 : iterate( $v1 ) )
   ASSIGN( $v1 : sf1( $v0 ) )
   plan__child
 
   where plan__parent does not use $v1 and $v0 is defined in plan__child.
   sf1 is a scalar function that has a unnesting implementation.
 
 After
 
   plan__parent
   UNNEST( $v2 : uf1( $v0 ) )
   plan__child
 

Author:

prestonc

Field Summary

Fields inherited from class org.apache.vxquery.compiler.rewriter.rules.AbstractUsedVariablesProcessingRule

hasRun, usedVariables

Constructor Summary

Constructors

Constructor	Description
ConvertAssignToUnnestRule()

Method Summary

Modifier and Type	Method	Description
protected boolean	processOperator(org.apache.commons.lang3.mutable.Mutable<org.apache.hyracks.algebricks.core.algebra.base.ILogicalOperator> opRef, org.apache.hyracks.algebricks.core.algebra.base.IOptimizationContext context)

Methods inherited from class org.apache.vxquery.compiler.rewriter.rules.AbstractUsedVariablesProcessingRule

rewritePost, rewritePre, rewritePreTrackingUsedVariables

Methods inherited from class java.lang.Object

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

Constructor Detail

ConvertAssignToUnnestRule

public ConvertAssignToUnnestRule()

Method Detail

processOperator

protected boolean processOperator(org.apache.commons.lang3.mutable.Mutable<org.apache.hyracks.algebricks.core.algebra.base.ILogicalOperator> opRef,
                                  org.apache.hyracks.algebricks.core.algebra.base.IOptimizationContext context)
                           throws org.apache.hyracks.algebricks.common.exceptions.AlgebricksException

Specified by:

processOperator in class AbstractUsedVariablesProcessingRule

Throws:

org.apache.hyracks.algebricks.common.exceptions.AlgebricksException