Flink:是否可以在X时间之后删除Queryable状态? [英] Flink: possible to delete Queryable state after X time?

问题描述

就我而言，我仅使用Flink的可查询状态.特别是，我不在乎检查点.

In my case, I use Flink's queryable state only. In particular, I do not care about checkpoints.

在发生事件时，我最多只能在X分钟后查询可查询状态.理想情况下，我将删除旧"状态以节省空间.

Upon an event, I query the queryable state only after a maximum of X minutes. Ideally, I would delete the "old" state to save on space.

这就是为什么我想知道:我可以在一段时间后发出Flink的状态以清除自身的信号吗?通过配置?通过特定的事件信号?怎么样?

That's why I wonder: can I signal Flink's state to clear itself after some time? Through configuration? Through specific event signals? How?

推荐答案

清除状态的一种方法是，当您不再需要特定键时，在状态对象(例如ValueState对象)上显式调用clear() .通常是在ProcessFunction的onTimer()回调中完成的.

One way to clear state is to explicitly call clear() on the state object (e.g., a ValueState object) when you no longer need it for a particular key. This is typically done in an onTimer() callback in a ProcessFunction.

另一种可能的方法是使用

Another possible approach would be to use state time-to-live to manage its lifecycle.

我还没有尝试过将状态TTL与可查询状态一起使用，但是我看不出它为什么不起作用的任何原因.但是，从Flink 1.7开始，状态TTL仅在访问状态(对于该键)或进行完整的状态快照时才真正清除状态(对于键).因此，在您的特定情况下，这种状态TTL机制可能不是很有用.

I haven't tried using state TTL with queryable state, but I can't see any reason why it shouldn't work. However, as of Flink 1.7, state TTL only actually clears state (for a key) when the state is accessed (for that key), or when taking a full state snapshot. So in your particular case, this state TTL mechanism may not be very useful.

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