org.apache.derby.impl.sql.execute
Class SystemAggregator

java.lang.Object
  extended byorg.apache.derby.impl.sql.execute.SystemAggregator
All Implemented Interfaces:
ExecAggregator, java.io.Externalizable, Formatable, java.io.Serializable, TypedFormat
Direct Known Subclasses:
CountAggregator, OrderableAggregator

abstract class SystemAggregator
extends java.lang.Object
implements ExecAggregator

Abstract aggregator that is extended by all internal (system) aggregators.

Author:
jamie

Field Summary
private  boolean eliminatedNulls
           
 
Constructor Summary
(package private) SystemAggregator()
           
 
Method Summary
protected abstract  void accumulate(DataValueDescriptor addend)
           
 void accumulate(DataValueDescriptor addend, java.lang.Object ga)
          Iteratively accumulates the addend into the aggregator.
 boolean didEliminateNulls()
          Return true if the aggregation eliminated at least one null from the input data set.
 void readExternal(java.io.ObjectInput in)
           
 void writeExternal(java.io.ObjectOutput out)
           
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface org.apache.derby.iapi.sql.execute.ExecAggregator
getResult, merge, newAggregator, setup
 
Methods inherited from interface org.apache.derby.iapi.services.io.TypedFormat
getTypeFormatId
 

Field Detail

eliminatedNulls

private boolean eliminatedNulls
Constructor Detail

SystemAggregator

SystemAggregator()
Method Detail

didEliminateNulls

public boolean didEliminateNulls()
Description copied from interface: ExecAggregator
Return true if the aggregation eliminated at least one null from the input data set.

Specified by:
didEliminateNulls in interface ExecAggregator

accumulate

public void accumulate(DataValueDescriptor addend,
                       java.lang.Object ga)
                throws StandardException
Description copied from interface: ExecAggregator
Iteratively accumulates the addend into the aggregator. Called on each member of the set of values that is being aggregated.

Specified by:
accumulate in interface ExecAggregator
Parameters:
addend - the DataValueDescriptor addend (current input to the aggregation)
ga - a result set getter
Throws:
StandardException - on error

accumulate

protected abstract void accumulate(DataValueDescriptor addend)
                            throws StandardException
Throws:
StandardException

writeExternal

public void writeExternal(java.io.ObjectOutput out)
                   throws java.io.IOException
Specified by:
writeExternal in interface java.io.Externalizable
Throws:
java.io.IOException

readExternal

public void readExternal(java.io.ObjectInput in)
                  throws java.io.IOException,
                         java.lang.ClassNotFoundException
Specified by:
readExternal in interface java.io.Externalizable
Throws:
java.io.IOException
java.lang.ClassNotFoundException

Built on Tue 2006-10-10 19:23:47+0200, from revision exported

Apache Derby V10.1 Engine Documentation - Copyright © 1997,2005 The Apache Software Foundation or its licensors, as applicable.