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Tag: flink-streaming

How to see restored value from savepoints?

I have tried to log info about states that recovered when I start a Flink app using savepoints. I see that the app was started using a savepoint correctly. But I can’t log state values that were recovered. The app calculates how many products were bought. Can I use CheckpointedFunction in such way? I see that context.isRestored() return true, but

What does latency metrics represent in Flink and are them really valid to evaluate the latency of an application?

I’ve a pipeline developed as shown below: I’m thinking hard about a way to value latency from input to output, but the relation between input and output isn’t 1 to 1 but there are a lot of transformations that make the latency evaluation conceptually very hard. I know about the latency metrics given by using the method: env.getConfig().setLatencyTrackingInterval(1000), but I

javadoc of SingleOutputStreamOperator#returns(TypeHint typeHint) method

I am reading the source code of SingleOutputStreamOperator#returns, its javadoc is: It mentions FunctionWithNonInferrableReturnType to show case the necessity of returns method, but I am unable to write such a class that is NonInferrableReturnType. Could you please help write a simple one? Thanks! Answer When the docs says NonInferrableReturnType it means that we can use the type variable <T>, or

Flink ElasticsearchSinkFunction not serializable in non-static method, but serializable in static method

I have a piece of code that only works inside static methods. If I put the code in a static method, then call it from a non-static method, it works. Never heard of anything like this and couldn’t find information online on it. This works: This doesn’t work: (Full) stack trace: The implementation of the provided ElasticsearchSinkFunction is not serializable.

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