Hi Dan, Currently, event-time TTL hasn't been supported due to implementation complexity and ambiguous semantics which need more discussion[1][2].
So people usually use state TTL with processing-time characteristics[3]. Could the processing-time ttl state meet your requirements in your case? If yes, you can refer the flink documentation[3][4] about how to use state TTL. [1] https://issues.apache.org/jira/browse/FLINK-12005 [2] https://lists.apache.org/thread/8nhs2dfthh6whstn1j200tpq7pbjx1lh [3] https://nightlies.apache.org/flink/flink-docs-release-1.14/docs/dev/datastream/fault-tolerance/state/#state-time-to-live-ttl [4] https://flink.apache.org/2019/05/19/state-ttl.html Best regards, Jinzhong, Li On 2022/01/10 04:39:43 Dan Hill wrote: > Hi. Any updates on this? > > How do people usually do TTLs? I want to add a backup TTL in case I have > leaky state. > > On Wed, Jun 17, 2020 at 6:08 AM Andrey Zagrebin <az...@apache.org> > wrote: > > > Hi Arti, > > > > Any program can use State with TTL but the state can only expire in > > processing time at the moment even if you configure event-time > > characteristics. > > As Congxian mentioned, the event time for TTL is planned. > > > > The cleanup says that it will not be removed 'by default'. The following > > sections [1] describe background cleanup which is not activated 'by > > default' in 1.9 but in 1.10. > > If you activate the background cleanup, you do not have to read the > > expired state to clean it up as if you have those timers you mentioned. > > See also the docs for details about background cleanup caveats. > > > > The timers approach is a valid way but heavy-weight in terms of storage > > because Flink will have to create a separate state for timers: > > key/timestamp. > > The timers approach is not implemented in Flink out-of-the-box at the > > moment. It can be implemented in the application as a simple background > > cleanup. > > > > Best, > > Andrey > > > > [1] > > https://ci.apache.org/projects/flink/flink-docs-release-1.9/dev/stream/state/state.html#cleanup-in-background > > > > On Wed, Jun 17, 2020 at 3:07 PM Congxian Qiu <qc...@gmail.com> > > wrote: > > > >> Hi > >> Currently, Flink does not support event-time TTL state, there is an > >> issue[1] tracking this. > >> [1] https://issues.apache.org/jira/browse/FLINK-12005 > >> Best, > >> Congxian > >> > >> > >> Arti Pande <pa...@gmail.com> 于2020年6月17日周三 下午7:37写道： > >> > >>> With Flink 1.9 is state TTL supported for event-time characteristics? This > >>> part > >>> <https://ci.apache.org/projects/flink/flink-docs-release-1.9/dev/stream/state/state.html#state-time-to-live-ttl> > >>> of the documentation says that > >>> > >>> > >>> - > >>> > >>> Only TTLs in reference to *processing time* are currently supported. > >>> > >>> Does this mean if a program uses event-time characteristics with > >>> stateful operators, it can not use TTL ?? > >>> > >>> Also clean up section > >>> <https://ci.apache.org/projects/flink/flink-docs-release-1.9/dev/stream/state/state.html#cleanup-of-expired-state> > >>> of > >>> the documentation says state values that are never read will never be > >>> cleared. > >>> [image: Screenshot 2020-06-17 at 5.00.41 PM.png] > >>> The question is, when processing a stream with unique elements or > >>> keys why would Flink framework expect the same key to be read in order for > >>> it to be removed after its expiration time ? Why does it not simply clean > >>> up the value for that key based on timers automatically without waiting > >>> for > >>> read operation from user code? > >>> > >>> Thanks > >>> Arti > >>> > >> >
