Kafka 流状态存储分布

Question

我有一个在多个实例上运行的 kafka 应用程序，我想使用状态存储来缓存一些数据字段。如果有多个应用程序实例，如果一个实例出现故障，一个实例的本地状态存储是否会复制到另一个实例？实例返回时会发生什么？状态存储如何连接到数据密钥以进行适当的重新分配？

Answer 1

if one instance goes down, does the local state store of one instance gets copied to other instance?

如果您没有备用副本，那么任务将从头开始读取更改日志主题以重建存储，有效地制作副本，是的。

In the docs,

Starting in 2.6, Kafka Streams will guarantee that a task is only ever assigned to an instance with a fully caught-up local copy of the state, if such an instance exists. Standby tasks will increase the likelihood that a caught-up instance exists in the case of a failure

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How are the state stores connected to the data keys for proper redistribution?

分区映射到任务线程（参考同一页）。