Hi there (asking again 😅), Are variables declared in an operator actually stored in checkpoints ?

Hi, what do you mean by

variables declared in an operator

? If you mean local variables or regular class properties - no. You need to use dedicated constructs to work with state: see https://nightlies.apache.org/flink/flink-docs-release-1.17/docs/dev/datastream/fault-tolerance/state/

Thanks Aleksandr, that's what I though !