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Table of Contents

Status

Current state:  "Under Discussion" Discarded (covered via KIP-258)

Discussion thread: TBD here

JIRA: KAFKA-4304

Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).

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Currently, when querying state store, it is not clear when the key was updated last. The ides of this JIRA is to make the latest update timestamp for each key-value-pair of the state store accessible.

For example, this might be useful to

  • check if a value was update but did not changed (just compare the update TS)
  • if you want to consider only recently updated keys

Public Interfaces

 

  • ReadOnlyKeyValueStore

    ReadOnlyKeyValueStoreWithKeyContext

Code Block
languagejava
longpublic getKeyTs(K key);
 
KeyContext<Kinterface ReadOnlyKeyValueStoreWithKeyContext<K, V> get(K key);  // we add this interface for use-cases where user will query for key and query for key timestamp again. To avoid double querying we overload get() methodextends ReadOnlyKeyValueStore<K, V> {
   KeyContext<K, V> getWithKeyContext(K key);
   KeyValueIterator<KeyContext<K, V>, V> rangeWithKeyContext(K from, K to);
   KeyValueIterator<KeyContext<K, V>, V> allWithKeyContext();
} 

Proposed Changes

We propose add a new interface KeyContext which will keep info about key. We can include more methods inside this context as well.

Code Block
languagejava
public interface KeyContext<K, V> {  // more key/value context can be added here as well.
   K key();
   V value();
   long keyTslastUpdated();
}

Compatibility, Deprecation, and Migration Plan

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