spring-cloud / spring-cloud/spring-cloud-stream

I want to consume KTable and materialize with optimization

Open
#2,886 0 comments 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

enhancement
Dominant language
Java
Stars
1.1k
Forks
646
Avg merge
2d 3h
Merged PRs (30d)
8

Description

When I consume KTable, it is materialized as KeyValueStore automatically.

fun process() = BiConsumer<KStream<String, String>, KTable<String, String>> { input, table ->
    input.join(table) { value1, value2 ->
        Pair(value1, value2)
    }.peek { key, value -> println("$key: $value") }
}

If I set topology.optimization to all then, changelog topic is not created but reuse consuming topic as changelog topic.
Because Kafka Streams join semantics, I want to change the type of state store to VersionedKeyValueStore.
If I materialize state store manually like this, it creates changelog topic although I set topology.optimization to all.

fun process() = BiConsumer<KStream<String, String>, KTable<String, String>> { input, table ->
    val storedTable = table
        .toStream()
        .groupByKey()
        .aggregate(
            { byteArrayOf() },
            { _, value, _ -> value.toByteArray() },
            Materialized.`as`(store)
        )
    val store = Stores.persistentVersionedKeyValueStore("kafka-streams-test-store", Duration.ofDays(1))
    val stream = input.join(storedTable) { value1, value2 ->
        Pair(value1, value2)
    }.peek { key, value -> println("$key, ${value?.first}, ${value?.second?.decodeToString()") }
}

Is there any way to change the type of state store with not creating changelog topic via optimization?

related so: https://stackoverflow.com/questions/77806593/how-to-change-state-store-type-of-ktable-from-keyvaluestore-to-versionedkeyvalue

Contributor guide

No contributing guide indexed for this repository

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the KTable join and materialization paths shown in the issue, then trace how topology.optimization=all handles the automatically materialized store versus the explicit VersionedKeyValueStore. The issue does not name source files or tests; done would require a documented or tested way to select the store type without creating an unnecessary changelog topic.

Written by the indexing model from the issue text.

Assessment

Tech stack
kafka, kotlin
Domain
stream-processing
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.