org.apache.kafka.streams.query

Class VersionedKeyQuery<K,V>

java.lang.Object

org.apache.kafka.streams.query.VersionedKeyQuery<K,V>

Type Parameters:

K - The type of the key.

V - The type of the value.

All Implemented Interfaces:

Query<VersionedRecord<V>>

@InterfaceStability.Evolving
public final class VersionedKeyQuery<K,V>
extends Object
implements Query<VersionedRecord<V>>

Interactive query for retrieving a single record from a versioned state store based on its key and timestamp.

Method Summary

Modifier and Type	Method and Description
VersionedKeyQuery<K,V>	asOf(Instant asOfTimestamp) Specifies the timestamp for the key query.
Optional<Instant>	asOfTimestamp() The timestamp of the query, if specified.
K	key() The key that was specified for this query.
static <K,V> VersionedKeyQuery<K,V>	withKey(K key) Creates a query that will retrieve the record from a versioned state store identified by key if it exists (or null otherwise).

Methods inherited from class java.lang.Object

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

Method Detail

withKey

public static <K,V> VersionedKeyQuery<K,V> withKey(K key)

Creates a query that will retrieve the record from a versioned state store identified by key if it exists (or null otherwise).

While the query by default returns the latest value of the specified key, setting the asOfTimestamp (by calling the asOf(Instant) method), makes the query to return the value associated to the specified asOfTimestamp.

Type Parameters:

K - The type of the key

V - The type of the value that will be retrieved

Parameters:

key - The key to retrieve

Throws:

NullPointerException - if key is null

asOf

public VersionedKeyQuery<K,V> asOf(Instant asOfTimestamp)

Specifies the timestamp for the key query. The key query returns the record's version for the specified timestamp. (To be more precise: The key query returns the record with the greatest timestamp <= asOfTimestamp)

Parameters:

asOfTimestamp - The timestamp of the query.

Throws:

NullPointerException - if asOfTimestamp is null

key

public K key()

The key that was specified for this query.

Returns:

The specified key of the query.

asOfTimestamp

public Optional<Instant> asOfTimestamp()

The timestamp of the query, if specified.

Returns:

The specified asOfTimestamp of the query.