org.apache.kafka.streams.state

Interface ReadOnlyWindowStore<K,V>

Type Parameters:

K - Type of keys

V - Type of values

All Known Subinterfaces:

WindowStore<K,V>

@InterfaceStability.Unstable
public interface ReadOnlyWindowStore<K,V>

A window store that only supports read operations Implementations should be thread-safe as concurrent reads and writes are expected.

Method Summary

Methods

Modifier and Type	Method and Description
WindowStoreIterator<V>	fetch(K key, long timeFrom, long timeTo) Get all the key-value pairs with the given key and the time range from all the existing windows.

Method Detail

fetch

WindowStoreIterator<V> fetch(K key,
                           long timeFrom,
                           long timeTo)

Get all the key-value pairs with the given key and the time range from all the existing windows.

The time range is inclusive and applies to the starting timestamp of the window. For example, if we have the following windows:

 +-------------------------------+
 |  key  | start time | end time |
 +-------+------------+----------+
 |   A   |     10     |    20    |
 +-------+------------+----------+
 |   A   |     15     |    25    |
 +-------+------------+----------+
 |   A   |     20     |    30    |
 +-------+------------+----------+
 |   A   |     25     |    35    |
 +--------------------------------
 

And we call store.fetch("A", 10, 20) then the results will contain the first three windows from the table above, i.e., all those where 10 <= start time <= 20.

Returns:

an iterator over key-value pairs <timestamp, value>

Throws:

InvalidStateStoreException - if the store is not initialized