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

Class IntroduceTwoStepAggregateRule

java.lang.Object

org.apache.vxquery.compiler.rewriter.rules.IntroduceTwoStepAggregateRule

All Implemented Interfaces:

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

public class IntroduceTwoStepAggregateRule
extends Object
implements org.apache.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule

The rule searches for aggregate operators with an aggregate function expression that has not been initialized for two step aggregation.

 Before
 
   plan__parent
   AGGREGATE( $v : af1( $v1 ) )
   plan__child
   
   Where af1 is a VXquery aggregate function expression configured for single 
   step processing and $v1 is defined in plan__child.
   
 After
 
   if (af1 == count) aggregate operating settings:
     Step 1: count
     Step 2: sum
   if (af1 == avg) aggregate operating settings:
     Step 1: avg-local
     Step 2: avg-global
   if (af1 in (max, min, sum)) aggregate operating settings:
     Step 1: af1
     Step 2: af1
 

Author:

prestonc

Constructor Summary

Constructors

Constructor	Description
IntroduceTwoStepAggregateRule()

Method Summary

Modifier and Type	Method	Description
boolean	rewritePost(org.apache.commons.lang3.mutable.Mutable<org.apache.hyracks.algebricks.core.algebra.base.ILogicalOperator> opRef, org.apache.hyracks.algebricks.core.algebra.base.IOptimizationContext context)
boolean	rewritePre(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 java.lang.Object

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

Constructor Detail

IntroduceTwoStepAggregateRule

public IntroduceTwoStepAggregateRule()

Method Detail

rewritePre

public boolean rewritePre(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:

rewritePre in interface org.apache.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule

Throws:

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

rewritePost

public boolean rewritePost(org.apache.commons.lang3.mutable.Mutable<org.apache.hyracks.algebricks.core.algebra.base.ILogicalOperator> opRef,
                           org.apache.hyracks.algebricks.core.algebra.base.IOptimizationContext context)

Specified by:

rewritePost in interface org.apache.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule