GenericAggregator (Apache Derby V10.14 Internals)

java.lang.Object
- org.apache.derby.impl.sql.execute.GenericAggregator

```
class GenericAggregator
extends java.lang.Object
```
Adaptor that sits between execution layer and aggregates.

Field Summary

Fields
Modifier and Type	Field	Description
`private AggregatorInfo`	`aggInfo`
`(package private) int`	`aggregatorColumnId`
`private ExecAggregator`	`cachedAggregator`
`private ClassFactory`	`cf`
`private int`	`inputColumnId`
`private int`	`resultColumnId`

Constructor Summary

Constructors
Constructor Description

GenericAggregator(AggregatorInfo aggInfo, ClassFactory cf)
Constructor:

Constructors
Constructor	Description
`GenericAggregator(AggregatorInfo aggInfo, ClassFactory cf)`	Constructor:

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`(package private) void`	`accumulate(java.lang.Object[] inputRow, java.lang.Object[] accumulateRow)`	Accumulate the aggregate results.
`(package private) void`	`accumulate(ExecRow inputRow, ExecRow accumulateRow)`	Accumulate the aggregate results.
`(package private) void`	`accumulate(DataValueDescriptor inputColumn, DataValueDescriptor aggregatorColumn)`	Accumulate the aggregate results.
`(package private) boolean`	`finish(ExecRow row)`	Get the results of the aggregation and put it in the result column.
`(package private) AggregatorInfo`	`getAggregatorInfo()`
`(package private) ExecAggregator`	`getAggregatorInstance()`	Get a new instance of the aggregator and initialize it.
`(package private) int`	`getColumnId()`	Return the column id that is being aggregated
`(package private) DataValueDescriptor`	`getInputColumnValue(ExecRow row)`
`(package private) void`	`initialize(ExecRow row)`	Initialize the aggregator
`(package private) void`	`merge(java.lang.Object[] inputRow, java.lang.Object[] mergeRow)`	Merge the aggregate results.
`(package private) void`	`merge(Storable aggregatorColumnIn, Storable aggregatorColumnOut)`	Merge two partial aggregations.
`(package private) void`	`merge(ExecRow inputRow, ExecRow mergeRow)`	Merge the aggregate results.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - aggInfo
```
private final AggregatorInfo aggInfo
```
  - aggregatorColumnId
```
int aggregatorColumnId
```
  - inputColumnId
```
private int inputColumnId
```
  - resultColumnId
```
private int resultColumnId
```
  - cf
```
private final ClassFactory cf
```
  - cachedAggregator
```
private ExecAggregator cachedAggregator
```
- Constructor Detail
  - GenericAggregator
```
GenericAggregator(AggregatorInfo aggInfo,
                  ClassFactory cf)
```
    Constructor:
    
    Parameters:
    
    aggInfo - information about the user aggregate
    
    cf - the class factory.
- Method Detail
  - initialize
```
void initialize(ExecRow row)
         throws StandardException
```
    Initialize the aggregator
    
    Parameters:
    
    row - the row with the aggregator to be initialized
    
    Throws:
    
    StandardException - on error
  - accumulate
```
void accumulate(ExecRow inputRow,
                ExecRow accumulateRow)
         throws StandardException
```
    Accumulate the aggregate results. This is the guts of the aggregation. We will call the user aggregate on itself to do the aggregation.
    
    Parameters:
    
    inputRow - the row with the input colum
    
    accumulateRow - the row with the aggregator
    
    Throws:
    
    StandardException - on error
  - accumulate
```
void accumulate(java.lang.Object[] inputRow,
                java.lang.Object[] accumulateRow)
         throws StandardException
```
    Accumulate the aggregate results. This is the guts of the aggregation. We will call the user aggregate on itself to do the aggregation.
    
    Parameters:
    
    inputRow - the row with the input colum
    
    accumulateRow - the row with the aggregator
    
    Throws:
    
    StandardException - on error
  - accumulate
```
void accumulate(DataValueDescriptor inputColumn,
                DataValueDescriptor aggregatorColumn)
         throws StandardException
```
    Accumulate the aggregate results. This is the guts of the aggregation. We will call the user aggregate on itself to do the aggregation.
    
    Parameters:
    
    inputColumn -
    
    aggregatorColumn -
    
    Throws:
    
    StandardException - on error
  - merge
```
void merge(ExecRow inputRow,
           ExecRow mergeRow)
    throws StandardException
```
    Merge the aggregate results. This is the guts of the aggregation. We will call the user aggregate on itself to do the aggregation.
    
    Parameters:
    
    inputRow - the row with the input colum
    
    mergeRow - the row with the aggregator
    
    Throws:
    
    StandardException - on error
  - merge
```
void merge(java.lang.Object[] inputRow,
           java.lang.Object[] mergeRow)
    throws StandardException
```
    Merge the aggregate results. This is the guts of the aggregation. We will call the user aggregate on itself to do the aggregation.
    
    Parameters:
    
    inputRow - the row with the input colum
    
    mergeRow - the row with the aggregator
    
    Throws:
    
    StandardException - on error
  - finish
```
boolean finish(ExecRow row)
        throws StandardException
```
    Get the results of the aggregation and put it in the result column.
    
    Parameters:
    
    row - the row with the result and the aggregator
    
    Throws:
    
    StandardException - on error
  - getAggregatorInstance
```
ExecAggregator getAggregatorInstance()
                              throws StandardException
```
    Get a new instance of the aggregator and initialize it.
    
    Returns:
    
    an exec aggregator
    
    Throws:
    
    StandardException - on error
  - getColumnId
```
int getColumnId()
```
    Return the column id that is being aggregated
  - getInputColumnValue
```
DataValueDescriptor getInputColumnValue(ExecRow row)
                                 throws StandardException
```
    Throws:
    
    StandardException
  - merge
```
void merge(Storable aggregatorColumnIn,
           Storable aggregatorColumnOut)
    throws StandardException
```
    Merge two partial aggregations. This is how the sorter merges partial aggregates.
    
    Throws:
    
    StandardException - on error
  - getAggregatorInfo
```
AggregatorInfo getAggregatorInfo()
```

Class GenericAggregator

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

aggInfo

aggregatorColumnId

inputColumnId

resultColumnId

cf

cachedAggregator

Constructor Detail

GenericAggregator

Method Detail

initialize

accumulate

accumulate

accumulate

merge

merge

finish

getAggregatorInstance

getColumnId

getInputColumnValue

merge

getAggregatorInfo