The trigger of State TTL

[lec ssmi]

    As we known, flink can set certain TTL config for the state, so that the state can be  automatically cleared after being idle for a period of time.

But if there is no new record coming in after setting  the TTL config , will the state be automatically cleared after a certain time? Or does it require a new  record  to trigger this clear operation ? 

 

Thanks! 

[Andrey Zagrebin-5]

Hi Lec Ssmi,

It depends on the state backend you use.

The heap state backend needs that either some state access happens or some records get processed in the operator [1].

The RocksDB requires that the state size is big enough (roughly speaking) to trigger the compaction process to clean the expired state [2].

Please, see the notes in the user documentation chapters referred by the suggested links.

Best,

Andrey

[1] https://ci.apache.org/projects/flink/flink-docs-release-1.10/dev/stream/state/state.html#incremental-cleanup

[2] https://ci.apache.org/projects/flink/flink-docs-release-1.10/dev/stream/state/state.html#cleanup-during-rocksdb-compaction

On Tue, Jun 2, 2020 at 5:23 PM lec ssmi <[hidden email]> wrote:

    As we known, flink can set certain TTL config for the state, so that the state can be  automatically cleared after being idle for a period of time.

But if there is no new record coming in after setting  the TTL config , will the state be automatically cleared after a certain time? Or does it require a new  record  to trigger this clear operation ? 

 

Thanks!