This has come up for Dataflow customers as well where people would like to directly serve the content that is stored in state and I'm not aware of any current plans to expose this from Beam at the moment.
You could implement this yourself by writing the value to state and also writing the value out to memcache (or other distributed key+value store) using window + user key as the memcache key but you may make the "state" viewable before it becomes "committed" in a Runner since processing of the bundle could be slow or could fail. If you need to have a point in time view of what the runner knows then you would need support from runners to be able to do this. On Mon, Nov 4, 2019 at 11:46 AM Dengpan Y <bytesstr...@gmail.com> wrote: > Hi, I recently see several Beam users using Samza Runner asking for a > tool/feature to query the internal state of PTransform, especially the > DoFn, for instance, the user can use the @StateId to define named state, > and the user would like to query the content of the state for a specific > key of that state. > > Does Beam have any plan to support this feature from Beam SDK, such as > develop a PTransform that can be wired into the pipeline so that the user > can query the state on demand? > Or If this has to be done on the Runner side, is there any best > practice/idea that we can follow? > > Thanks > Dengpan > >
