SystemAggregator (Apache Derby V10.14 Internals)

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

Fields
Modifier and Type	Field	Description
`private boolean`	`eliminatedNulls`

Constructor Summary

Constructors
Constructor Description

SystemAggregator()

Constructors
Constructor	Description
`SystemAggregator()`

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
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 interface org.apache.derby.iapi.sql.execute.ExecAggregator
getResult, merge, newAggregator, setup

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.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

Class SystemAggregator

Field Summary

Constructor Summary

Method Summary

Methods inherited from interface org.apache.derby.iapi.sql.execute.ExecAggregator

Methods inherited from class java.lang.Object

Methods inherited from interface org.apache.derby.iapi.services.io.TypedFormat

Field Detail

eliminatedNulls

Constructor Detail

SystemAggregator

Method Detail

didEliminateNulls

accumulate

accumulate

writeExternal

readExternal

toString