AggregatorInfo (Apache Derby V10.14 Internals)

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

All Implemented Interfaces:

java.io.Externalizable, java.io.Serializable, Formatable, TypedFormat
```
public class AggregatorInfo
extends java.lang.Object
implements Formatable
```
This is a simple class used to store the run time information needed to invoke an aggregator. This class is serializable because it is stored with the plan. It is serializable rather than externalizable because it isn't particularly complicated and presumbably we don't need version control on plans.

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type	Field	Description
`(package private) java.lang.String`	`aggregateName`	This class implements Formatable.
`(package private) java.lang.String`	`aggregatorClassName`
`(package private) int`	`aggregatorColumn`
`(package private) int`	`inputColumn`
`(package private) boolean`	`isDistinct`
`(package private) int`	`outputColumn`
`(package private) ResultDescription`	`rd`

Constructor Summary

Constructors
Constructor	Description
`AggregatorInfo()`	Niladic constructor for Formattable
`AggregatorInfo(java.lang.String aggregateName, java.lang.String aggregatorClassName, int inputColNum, int outputColNum, int aggregatorColNum, boolean isDistinct, ResultDescription rd)`	Consructor

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`java.lang.String`	`getAggregateName()`	Get the name of the aggergate (e.g.
`java.lang.String`	`getAggregatorClassName()`	Get the name of the class that implements the user aggregator for this class.
`int`	`getAggregatorColNum()`	Get the column number for the aggregator column.
`int`	`getInputColNum()`	Get the column number for the input (addend) column.
`int`	`getOutputColNum()`	Get the column number for the output (result) column.
`ResultDescription`	`getResultDescription()`	Get the result description for the input value to this aggregate.
`int`	`getTypeFormatId()`	Get the formatID which corresponds to this class.
`boolean`	`isDistinct()`	Is the aggergate distinct
`void`	`readExternal(java.io.ObjectInput in)`	Read this object from a stream of stored objects.
`java.lang.String`	`toString()`	Get a string for the object
`void`	`writeExternal(java.io.ObjectOutput out)`	Write this object out

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

- Field Detail
  - aggregateName
```
java.lang.String aggregateName
```
    This class implements Formatable. That means that it can write itself to and from a formatted stream. If you add more fields to this class, make sure that you also write/read them with the writeExternal()/readExternal() methods. If, inbetween releases, you add more fields to this class, then you should bump the version number emitted by the getTypeFormatId() method. OR, since this is something that is used in stored prepared statements, it is ok to change it if you make sure that stored prepared statements are invalidated across releases.
  - inputColumn
```
int inputColumn
```
  - outputColumn
```
int outputColumn
```
  - aggregatorColumn
```
int aggregatorColumn
```
  - aggregatorClassName
```
java.lang.String aggregatorClassName
```
  - isDistinct
```
boolean isDistinct
```
  - rd
```
ResultDescription rd
```
- Constructor Detail
  - AggregatorInfo
```
public AggregatorInfo()
```
    Niladic constructor for Formattable
  - AggregatorInfo
```
public AggregatorInfo(java.lang.String aggregateName,
                      java.lang.String aggregatorClassName,
                      int inputColNum,
                      int outputColNum,
                      int aggregatorColNum,
                      boolean isDistinct,
                      ResultDescription rd)
```
    Consructor
    
    Parameters:
    
    aggregateName - the name of the aggregate. Not actually used anywhere except diagnostics. Should be the names as found in the language (e.g. MAX).
    
    aggregatorClassName - the name of the aggregator used to process this aggregate. Aggregator expected to have a null arg constructor and implement Aggregator.
    
    inputColNum - the input column number
    
    outputColNum - the output column number
    
    aggregatorColNum - the column number in which the aggregator is stored.
    
    isDistinct - if it is a distinct aggregate
    
    rd - the result description
- Method Detail
  - getAggregateName
```
public java.lang.String getAggregateName()
```
    Get the name of the aggergate (e.g. MAX)
    
    Returns:
    
    the aggeregate name
  - getAggregatorClassName
```
public java.lang.String getAggregatorClassName()
```
    Get the name of the class that implements the user aggregator for this class.
    
    Returns:
    
    the aggeregator class name
  - getAggregatorColNum
```
public int getAggregatorColNum()
```
    Get the column number for the aggregator column.
    
    Returns:
    
    the aggeregator colid
  - getInputColNum
```
public int getInputColNum()
```
    Get the column number for the input (addend) column.
    
    Returns:
    
    the aggeregator colid
  - getOutputColNum
```
public int getOutputColNum()
```
    Get the column number for the output (result) column.
    
    Returns:
    
    the aggeregator colid
  - isDistinct
```
public boolean isDistinct()
```
    Is the aggergate distinct
    
    Returns:
    
    whether it is distinct
  - getResultDescription
```
public ResultDescription getResultDescription()
```
    Get the result description for the input value to this aggregate.
    
    Returns:
    
    the rd
  - toString
```
public java.lang.String toString()
```
    Get a string for the object
    
    Overrides:
    
    toString in class java.lang.Object
    
    Returns:
    
    string
  - writeExternal
```
public void writeExternal(java.io.ObjectOutput out)
                   throws java.io.IOException
```
    Write this object out
    
    Specified by:
    
    writeExternal in interface java.io.Externalizable
    
    Parameters:
    
    out - write bytes here
    
    Throws:
    
    java.io.IOException - thrown on error
  - readExternal
```
public void readExternal(java.io.ObjectInput in)
                  throws java.io.IOException,
                         java.lang.ClassNotFoundException
```
    Read this object from a stream of stored objects.
    
    Specified by:
    
    readExternal in interface java.io.Externalizable
    
    Parameters:
    
    in - read this.
    
    Throws:
    
    java.io.IOException - thrown on error
    
    java.lang.ClassNotFoundException - thrown on error
  - getTypeFormatId
```
public int getTypeFormatId()
```
    Get the formatID which corresponds to this class.
    
    Specified by:
    
    getTypeFormatId in interface TypedFormat
    
    Returns:
    
    the formatID of this class

Class AggregatorInfo

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

aggregateName

inputColumn

outputColumn

aggregatorColumn

aggregatorClassName

isDistinct

rd

Constructor Detail

AggregatorInfo

AggregatorInfo

Method Detail

getAggregateName

getAggregatorClassName

getAggregatorColNum

getInputColNum

getOutputColNum

isDistinct

getResultDescription

toString

writeExternal

readExternal

getTypeFormatId