org.apache.flink.table.runtime.keyselector

Class NullBinaryRowKeySelector

java.lang.Object

org.apache.flink.table.runtime.keyselector.NullBinaryRowKeySelector

All Implemented Interfaces:

Serializable, Function, KeySelector<BaseRow,BaseRow>, ResultTypeQueryable<BaseRow>, BaseRowKeySelector

public class NullBinaryRowKeySelector
extends Object
implements BaseRowKeySelector

A utility class which key is always empty no matter what the input row is.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static NullBinaryRowKeySelector	INSTANCE

Constructor Summary

Constructors

Constructor and Description
NullBinaryRowKeySelector()

Method Summary

Modifier and Type	Method and Description
BaseRow	getKey(BaseRow value) User-defined function that deterministically extracts the key from an object.
BaseRowTypeInfo	getProducedType() Gets the data type (as a TypeInformation) produced by this function or input format.

Methods inherited from class java.lang.Object

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

Field Detail

INSTANCE

public static final NullBinaryRowKeySelector INSTANCE

Constructor Detail

NullBinaryRowKeySelector

public NullBinaryRowKeySelector()

Method Detail

getKey

public BaseRow getKey(BaseRow value)
               throws Exception

Description copied from interface: KeySelector

User-defined function that deterministically extracts the key from an object.

For example for a class:

        public class Word {
                String word;
                int count;
        }
 

The key extractor could return the word as a key to group all Word objects by the String they contain.

The code would look like this

        public String getKey(Word w) {
                return w.word;
        }
 

Specified by:

getKey in interface KeySelector<BaseRow,BaseRow>

Parameters:

value - The object to get the key from.

Returns:

The extracted key.

Throws:

Exception - Throwing an exception will cause the execution of the respective task to fail, and trigger recovery or cancellation of the program.

getProducedType

public BaseRowTypeInfo getProducedType()

Description copied from interface: ResultTypeQueryable

Gets the data type (as a TypeInformation) produced by this function or input format.

Specified by:

getProducedType in interface ResultTypeQueryable<BaseRow>

Specified by:

getProducedType in interface BaseRowKeySelector

Returns:

The data type produced by this function or input format.