[
https://issues.apache.org/jira/browse/KAFKA-14976?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
A. Sophie Blee-Goldman updated KAFKA-14976:
-------------------------------------------
Labels: kip (was: needs-kip)
> Left/outer stream-stream joins create KV stores that aren't customizable
> ------------------------------------------------------------------------
>
> Key: KAFKA-14976
> URL: https://issues.apache.org/jira/browse/KAFKA-14976
> Project: Kafka
> Issue Type: Bug
> Components: streams
> Reporter: A. Sophie Blee-Goldman
> Assignee: Almog Gavra
> Priority: Major
> Labels: kip
>
> It appears that we only give the illusion of full customizability when it
> comes to the state stores of a windowed join. This arose due to an
> [optimization|https://github.com/apache/kafka/pull/11252] for the performance
> of the spurious results fix, and means that these joins now come with one
> additional, and possibly unexpected, state store:
>
> {code:java}
> final StoreBuilder<KeyValueStore<TimestampedKeyAndJoinSide<K>,
> LeftOrRightValue<V1, V2>>> builder =
> new ListValueStoreBuilder<>(
> |--[ persistent ?
> this--> | Stores.persistentKeyValueStore(storeName) :
> |--[ Stores.inMemoryKeyValueStore(storeName),
> timestampedKeyAndJoinSideSerde,
> leftOrRightValueSerde,
> Time.SYSTEM
> ); {code}
>
> where persistent is defined above that as
> {code:java}
> final boolean persistent = streamJoinedInternal.thisStoreSupplier() == null
> || streamJoinedInternal.thisStoreSupplier().get().persistent(); {code}
>
> This means regardless of whether a custom state store implementation was
> passed in to the join, we will still insert one of our RocksDB or InMemory
> state stores. Which might be very surprising since the API makes it seem like
> the underlying stores are fully configurable.
> I'm adding a warning line for this in PR
> [#13682|https://github.com/apache/kafka/pull/13682/files#diff-9ce43046fdef1233ab762e728abd1d3d44d7c270b28dcf6b63aa31a93a30af07R334-R336]
> but we should really make this hidden state store fully configurable like
> the window stores currently are (which will require a KIP)
>
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
