Hi Dongwoo
This can be quite confusing. Before Flink 1.13, Flink's statebackend was actually a hybrid concept that included three types of statebackends: *MemoryStateBackend*, *FsStateBackend*, and *RocksDBStateBackend*. The default *MemoryStateBackend* uses heap as the backend, and the state is stored in jobManger. You can refer to this migration document for more information: https://nightlies.apache.org/flink/flink-docs-master/docs/ops/state/state_backends/#migrating-from-legacy-backends . Best Feng On Sun, Apr 9, 2023 at 10:23 PM Dongwoo Kim <dongwoo7....@gmail.com> wrote: > Hi community, I’m new to flink and trying to learn about the concepts of > flink to prepare migrating heron application to flink. > I have a quick question about this flink document. > ( > https://nightlies.apache.org/flink/flink-docs-release-1.17/docs/concepts/stateful-stream-processing/#snapshotting-operator-state > ) > > What I understood is states are stored in configured state backend which > can be either task manager’s heap or rocksdb. > And snapshots of checkpoint is stored by default in job manager’s heap and > mostly in distributed file system. > But in the document it says like below and it is confusing to me. Isn’t > the second line talking about checkpoint storage or checkpoint backend? Not > state backend? Thanks in advance, enjoy your weekend! > > *"Because the state of a snapshot may be large, it is stored in a > configurable state backend > <https://nightlies.apache.org/flink/flink-docs-release-1.17/docs/ops/state/state_backends/>. > By default, this is the JobManager’s memory, but for production use a > distributed reliable storage should be configured (such as HDFS)” * >
