Package org.apache.derby.impl.sql.execute

Class SystemAggregator

java.lang.Object

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

All Implemented Interfaces:

java.io.Externalizable, java.io.Serializable, Formatable, TypedFormat, ExecAggregator

Direct Known Subclasses:

CountAggregator, OrderableAggregator

abstract class SystemAggregator
extends java.lang.Object
implements ExecAggregator

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

Field Summary

Fields

Modifier and Type	Field	Description
private boolean	eliminatedNulls

Constructor Summary

Constructors

Constructor	Description
SystemAggregator()

Method Summary

Modifier and Type	Method	Description
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)
java.lang.String	toString()
void	writeExternal(java.io.ObjectOutput out)

Methods inherited from class java.lang.Object

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

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object