Package org.apache.flink.state.api

Class SavepointReader

java.lang.Object

org.apache.flink.state.api.SavepointReader

@PublicEvolving
public class SavepointReader
extends Object

The entry point for reading state from a Flink savepoint.

Method Summary

Modifier and Type	Method	Description
static SavepointReader	read(StreamExecutionEnvironment env, String path)	Loads an existing savepoint.
static SavepointReader	read(StreamExecutionEnvironment env, String path, StateBackend stateBackend)	Loads an existing savepoint.
<K,V> DataStream<Tuple2<K,V>>	readBroadcastState(OperatorIdentifier identifier, String name, TypeInformation<K> keyTypeInfo, TypeInformation<V> valueTypeInfo)	Read operator BroadcastState from a Savepoint.
<K,V> DataStream<Tuple2<K,V>>	readBroadcastState(OperatorIdentifier identifier, String name, TypeInformation<K> keyTypeInfo, TypeInformation<V> valueTypeInfo, TypeSerializer<K> keySerializer, TypeSerializer<V> valueSerializer)	Read operator BroadcastState from a Savepoint when a custom serializer was used; e.g., a different serializer than the one returned by TypeInformation#createSerializer.
<K,OUT> DataStream<OUT>	readKeyedState(OperatorIdentifier identifier, KeyedStateReaderFunction<K,OUT> function)	Read keyed state from an operator in a Savepoint.
<K,OUT> DataStream<OUT>	readKeyedState(OperatorIdentifier identifier, KeyedStateReaderFunction<K,OUT> function, TypeInformation<K> keyTypeInfo, TypeInformation<OUT> outTypeInfo)	Read keyed state from an operator in a Savepoint.
<T> DataStream<T>	readListState(OperatorIdentifier identifier, String name, TypeInformation<T> typeInfo)	Read operator ListState from a Savepoint.
<T> DataStream<T>	readListState(OperatorIdentifier identifier, String name, TypeInformation<T> typeInfo, TypeSerializer<T> serializer)	Read operator ListState from a Savepoint when a custom serializer was used; e.g., a different serializer than the one returned by TypeInformation#createSerializer.
<T> DataStream<T>	readUnionState(OperatorIdentifier identifier, String name, TypeInformation<T> typeInfo)	Read operator UnionState from a Savepoint.
<T> DataStream<T>	readUnionState(OperatorIdentifier identifier, String name, TypeInformation<T> typeInfo, TypeSerializer<T> serializer)	Read operator UnionState from a Savepoint when a custom serializer was used; e.g., a different serializer than the one returned by TypeInformation#createSerializer.
<W extends Window> WindowSavepointReader<W>	window(TypeSerializer<W> windowSerializer)	Read window state from an operator in a Savepoint.
<W extends Window> WindowSavepointReader<W>	window(WindowAssigner<?,W> assigner)	Read window state from an operator in a Savepoint.

Methods inherited from class java.lang.Object

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

Method Detail

read

public static SavepointReader read(StreamExecutionEnvironment env,
                                   String path)
                            throws IOException

Loads an existing savepoint. Useful if you want to query the state of an existing application. The savepoint will be read using the state backend defined via the clusters configuration.

Parameters:

env - The execution environment used to transform the savepoint.

path - The path to an existing savepoint on disk.

Returns:

A SavepointReader.

Throws:

IOException

read

public static SavepointReader read(StreamExecutionEnvironment env,
                                   String path,
                                   StateBackend stateBackend)
                            throws IOException

Loads an existing savepoint. Useful if you want to query the state of an existing application.

Parameters:

env - The execution environment used to transform the savepoint.

path - The path to an existing savepoint on disk.

stateBackend - The state backend of the savepoint.

Returns:

A SavepointReader.

Throws:

IOException

readListState

public <T> DataStream<T> readListState(OperatorIdentifier identifier,
                                       String name,
                                       TypeInformation<T> typeInfo)
                                throws IOException

Read operator ListState from a Savepoint.

Type Parameters:

T - The type of the values that are in the list state.

Parameters:

identifier - The identifier of the operator.

name - The (unique) name for the state.

typeInfo - The type of the elements in the state.

Returns:

A DataStream representing the elements in state.

Throws:

IOException - If the savepoint path is invalid or the uid does not exist.

readListState

public <T> DataStream<T> readListState(OperatorIdentifier identifier,
                                       String name,
                                       TypeInformation<T> typeInfo,
                                       TypeSerializer<T> serializer)
                                throws IOException

Read operator ListState from a Savepoint when a custom serializer was used; e.g., a different serializer than the one returned by TypeInformation#createSerializer.

Type Parameters:

T - The type of the values that are in the list state.

Parameters:

identifier - The identifier of the operator.

name - The (unique) name for the state.

typeInfo - The type of the elements in the state.

serializer - The serializer used to write the elements into state.

Returns:

A DataStream representing the elements in state.

Throws:

IOException - If the savepoint path is invalid or the uid does not exist.

readUnionState

public <T> DataStream<T> readUnionState(OperatorIdentifier identifier,
                                        String name,
                                        TypeInformation<T> typeInfo)
                                 throws IOException

Read operator UnionState from a Savepoint.

Type Parameters:

T - The type of the values that are in the union state.

Parameters:

identifier - The identifier of the operator.

name - The (unique) name for the state.

typeInfo - The type of the elements in the state.

Returns:

A DataStream representing the elements in state.

Throws:

IOException - If the savepoint path is invalid or the uid does not exist.

readUnionState

public <T> DataStream<T> readUnionState(OperatorIdentifier identifier,
                                        String name,
                                        TypeInformation<T> typeInfo,
                                        TypeSerializer<T> serializer)
                                 throws IOException

Read operator UnionState from a Savepoint when a custom serializer was used; e.g., a different serializer than the one returned by TypeInformation#createSerializer.

Type Parameters:

T - The type of the values that are in the union state.

Parameters:

identifier - The identifier of the operator.

name - The (unique) name for the state.

typeInfo - The type of the elements in the state.

serializer - The serializer used to write the elements into state.

Returns:

A DataStream representing the elements in state.

Throws:

IOException - If the savepoint path is invalid or the uid does not exist.

readBroadcastState

public <K,V> DataStream<Tuple2<K,V>> readBroadcastState(OperatorIdentifier identifier,
                                                                    String name,
                                                                    TypeInformation<K> keyTypeInfo,
                                                                    TypeInformation<V> valueTypeInfo)
                                                             throws IOException

Read operator BroadcastState from a Savepoint.

Type Parameters:

K - The type of keys in state.

V - The type of values in state.

Parameters:

identifier - The identifier of the operator.

name - The (unique) name for the state.

keyTypeInfo - The type information for the keys in the state.

valueTypeInfo - The type information for the values in the state.

Returns:

A DataStream of key-value pairs from state.

Throws:

IOException - If the savepoint does not contain the specified uid.

readBroadcastState

public <K,V> DataStream<Tuple2<K,V>> readBroadcastState(OperatorIdentifier identifier,
                                                                    String name,
                                                                    TypeInformation<K> keyTypeInfo,
                                                                    TypeInformation<V> valueTypeInfo,
                                                                    TypeSerializer<K> keySerializer,
                                                                    TypeSerializer<V> valueSerializer)
                                                             throws IOException

Read operator BroadcastState from a Savepoint when a custom serializer was used; e.g., a different serializer than the one returned by TypeInformation#createSerializer.

Type Parameters:

K - The type of keys in state.

V - The type of values in state.

Parameters:

identifier - The identifier of the operator.

name - The (unique) name for the state.

keyTypeInfo - The type information for the keys in the state.

valueTypeInfo - The type information for the values in the state.

keySerializer - The type serializer used to write keys into the state.

valueSerializer - The type serializer used to write values into the state.

Returns:

A DataStream of key-value pairs from state.

Throws:

IOException - If the savepoint path is invalid or the uid does not exist.

readKeyedState

public <K,OUT> DataStream<OUT> readKeyedState(OperatorIdentifier identifier,
                                                    KeyedStateReaderFunction<K,OUT> function)
                                             throws IOException

Read keyed state from an operator in a Savepoint.

Type Parameters:

K - The type of the key in state.

OUT - The output type of the transform function.

Parameters:

identifier - The identifier of the operator.

function - The KeyedStateReaderFunction that is called for each key in state.

Returns:

A DataStream of objects read from keyed state.

Throws:

IOException - If the savepoint does not contain operator state with the given uid.

readKeyedState

public <K,OUT> DataStream<OUT> readKeyedState(OperatorIdentifier identifier,
                                                    KeyedStateReaderFunction<K,OUT> function,
                                                    TypeInformation<K> keyTypeInfo,
                                                    TypeInformation<OUT> outTypeInfo)
                                             throws IOException

Read keyed state from an operator in a Savepoint.

Type Parameters:

K - The type of the key in state.

OUT - The output type of the transform function.

Parameters:

identifier - The identifier of the operator.

function - The KeyedStateReaderFunction that is called for each key in state.

keyTypeInfo - The type information of the key in state.

outTypeInfo - The type information of the output of the transform reader function.

Returns:

A DataStream of objects read from keyed state.

Throws:

IOException - If the savepoint does not contain operator state with the given uid.

window

public <W extends Window> WindowSavepointReader<W> window(WindowAssigner<?,W> assigner)

Read window state from an operator in a Savepoint. This method supports reading from any type of window.

Parameters:

assigner - The WindowAssigner used to write out the operator.

Returns:

A WindowSavepointReader.

window

public <W extends Window> WindowSavepointReader<W> window(TypeSerializer<W> windowSerializer)

Read window state from an operator in a Savepoint. This method supports reading from any type of window.

Parameters:

windowSerializer - The serializer used for the window type.

Returns:

A WindowSavepointReader.