Status

Current state: Discarded (covered via KIP-258)

Discussion thread: here

JIRA: KAFKA-4304

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

Motivation

Taken from related issue:

 

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

 

  • ReadOnlyKeyValueStoreWithKeyContext

public interface ReadOnlyKeyValueStoreWithKeyContext<K, V> extends 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.

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

Compatibility, Deprecation, and Migration Plan

Not yet

Rejected Alternatives

Not yet

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