What function are you implementing and how are you using it? Usually it’s enough if your function implements RichFunction (or rather extend from AbstractRichFunction) and then you could use RichFunction#open in the similar manner as in the code that I posted in previous message. Flink in many places performs instanceof chekcs like: org.apache.flink.api.common.functions.util.FunctionUtils#openFunction
public static void openFunction(Function function, Configuration parameters) throws Exception{ if (function instanceof RichFunction) { RichFunction richFunction = (RichFunction) function; richFunction.open(parameters); } } Piotrek > On 7 Jun 2018, at 11:07, Tony Wei <tony19920...@gmail.com> wrote: > > Hi Piotrek, > > It seems that this was implemented by `Operator` API, which is a more low > level api compared to `Function` API. > Since in `Function` API level we can only migrate state by event triggered, > it is more convenient in this way to migrate state by foreach all keys in > `open()` method. > If I was implemented state operator by `ProcessFunction` API, is it possible > to port it to `KeyedProcessOperator` and do the state migration that you > mentioned? > And are there something concerned and difficulties that will leads to > restored state failed or other problems? Thank you! > > Best Regards, > Tony Wei > > 2018-06-07 16:10 GMT+08:00 Piotr Nowojski <pi...@data-artisans.com > <mailto:pi...@data-artisans.com>>: > Hi, > > General solution for state/schema migration is under development and it might > be released with Flink 1.6.0. > > Before that, you need to manually handle the state migration in your > operator’s open method. Lets assume that your OperatorV1 has a state field > “stateV1”. Your OperatorV2 defines field “stateV2”, which is incompatible > with previous version. What you can do, is to add a logic in open method, to > check: > 1. If “stateV2” is non empty, do nothing > 2. If there is no “stateV2”, iterate over all of the keys and manually > migrate “stateV1” to “stateV2” > > In your OperatorV3 you could drop the support for “stateV1”. > > I have once implemented something like that here: > > https://github.com/pnowojski/flink/blob/bfc8858fc4b9125b8fc7acd03cb3f95c000926b2/flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/operators/windowing/WindowOperator.java#L258 > > <https://github.com/pnowojski/flink/blob/bfc8858fc4b9125b8fc7acd03cb3f95c000926b2/flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/operators/windowing/WindowOperator.java#L258> > > Hope that helps! > > Piotrek > > >> On 6 Jun 2018, at 17:04, TechnoMage <mla...@technomage.com >> <mailto:mla...@technomage.com>> wrote: >> >> We are still pretty new to Flink and I have a conceptual / DevOps question. >> >> When a job is modified and we want to deploy the new version, what is the >> preferred method? Our jobs have a lot of keyed state. >> >> If we use snapshots we have old state that may no longer apply to the new >> pipeline. >> If we start a new job we can reprocess historical data from Kafka, but that >> can be very resource heavy for a while. >> >> Is there an option I am missing? Are there facilities to “patch” or “purge” >> selectively the keyed state? >> >> Michael > >