Package org.apache.flink.table.runtime.sequencedmultisetstate.linked

Class LinkedMultiSetState

java.lang.Object

org.apache.flink.table.runtime.sequencedmultisetstate.linked.LinkedMultiSetState

All Implemented Interfaces:

SequencedMultiSetState<org.apache.flink.table.data.RowData>

@Internal
public class LinkedMultiSetState
extends Object
implements SequencedMultiSetState<org.apache.flink.table.data.RowData>

This class implements an ordered multi-set state backend using Flink's state primitives. It maintains the insertion order of elements and supports operations such as adding, appending, and removing elements. The state is backed by Flink's `MapState` and `ValueState` to store and manage the relationships between rows and sequence numbers (SQNs).

Key features of this state implementation:

• Maintains insertion order of elements using a doubly-linked list structure.
• Supports both normal set semantics (replacing existing elements) and multi-set semantics (allowing duplicates).
• Efficiently tracks the highest sequence number and links between elements for fast traversal and updates.
• Provides methods to add, append, and remove elements with appropriate handling of state transitions.

Note: This implementation is marked as @Internal and is intended for internal use within Flink. It may be subject to changes in future versions.

Usage:

• Use the add(RowData, long) method to add an element, replacing any existing matching element.
• Use the append(RowData, long) method to append an element, allowing duplicates.
• Use the remove(RowData) method to remove an element, with detailed removal result types.

See Also:

SequencedMultiSetState, MapState, ValueState

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.flink.table.runtime.sequencedmultisetstate.SequencedMultiSetState

SequencedMultiSetState.StateChangeInfo<T>, SequencedMultiSetState.StateChangeType, SequencedMultiSetState.Strategy

Method Summary

Modifier and Type	Method	Description
SequencedMultiSetState.StateChangeInfo<org.apache.flink.table.data.RowData>	add(org.apache.flink.table.data.RowData row, long timestamp)	Add the given element using the normal (non-multi) set semantics: if a matching element exists already, replace it (the timestamp is updated).
SequencedMultiSetState.StateChangeInfo<org.apache.flink.table.data.RowData>	append(org.apache.flink.table.data.RowData row, long timestamp)	Add the given element using the multi-set semantics, i.e. append.
void	clear()	Clear the state (in the current key context).
void	clearCache()	Clear caches.
static LinkedMultiSetState	create(SequencedMultiSetStateContext p, org.apache.flink.api.common.functions.RuntimeContext ctx)
boolean	isEmpty()	Tells whether any state exists (in the given key context).
Iterator<org.apache.flink.api.java.tuple.Tuple2<org.apache.flink.table.data.RowData,Long>>	iterator()	Get iterator over all remaining elements and their timestamps, in order of insertion.
void	loadCache()	Load cache.
SequencedMultiSetState.StateChangeInfo<org.apache.flink.table.data.RowData>	remove(org.apache.flink.table.data.RowData row)	Remove the given element.

Methods inherited from class java.lang.Object

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

Method Detail

create

public static LinkedMultiSetState create(SequencedMultiSetStateContext p,
                                         org.apache.flink.api.common.functions.RuntimeContext ctx)

add

public SequencedMultiSetState.StateChangeInfo<org.apache.flink.table.data.RowData> add(org.apache.flink.table.data.RowData row,
                                                                                       long timestamp)
                                                                                throws Exception

Description copied from interface: SequencedMultiSetState

Add the given element using the normal (non-multi) set semantics: if a matching element exists already, replace it (the timestamp is updated).

Specified by:

add in interface SequencedMultiSetState<org.apache.flink.table.data.RowData>

Throws:

Exception

append

public SequencedMultiSetState.StateChangeInfo<org.apache.flink.table.data.RowData> append(org.apache.flink.table.data.RowData row,
                                                                                          long timestamp)
                                                                                   throws Exception

Description copied from interface: SequencedMultiSetState

Add the given element using the multi-set semantics, i.e. append.

Specified by:

append in interface SequencedMultiSetState<org.apache.flink.table.data.RowData>

Throws:

Exception

remove

public SequencedMultiSetState.StateChangeInfo<org.apache.flink.table.data.RowData> remove(org.apache.flink.table.data.RowData row)
                                                                                   throws Exception

Description copied from interface: SequencedMultiSetState

Remove the given element. If there are multiple instances of the same element, remove the first one in insertion order.

Specified by:

remove in interface SequencedMultiSetState<org.apache.flink.table.data.RowData>

Throws:

Exception

clear

public void clear()

Description copied from interface: SequencedMultiSetState

Clear the state (in the current key context).

Specified by:

clear in interface SequencedMultiSetState<org.apache.flink.table.data.RowData>

loadCache

public void loadCache()

Description copied from interface: SequencedMultiSetState

Load cache.

Specified by:

loadCache in interface SequencedMultiSetState<org.apache.flink.table.data.RowData>

clearCache

public void clearCache()

Description copied from interface: SequencedMultiSetState

Clear caches.

Specified by:

clearCache in interface SequencedMultiSetState<org.apache.flink.table.data.RowData>

iterator

public Iterator<org.apache.flink.api.java.tuple.Tuple2<org.apache.flink.table.data.RowData,Long>> iterator()
                                                                                                          throws Exception

Description copied from interface: SequencedMultiSetState

Get iterator over all remaining elements and their timestamps, in order of insertion.

Specified by:

iterator in interface SequencedMultiSetState<org.apache.flink.table.data.RowData>

Throws:

Exception

isEmpty

public boolean isEmpty()
                throws IOException

Description copied from interface: SequencedMultiSetState

Tells whether any state exists (in the given key context).

Specified by:

isEmpty in interface SequencedMultiSetState<org.apache.flink.table.data.RowData>

Throws:

IOException