Hi Mengqi, if what you are trying to do is output the solution set of every iteration, before the iteration has finished, then that is not possible. i.e. you can not output the solution set to a sink or another operator during the iteration.
However, you can add elements to the solution set and grow the dataset as the iteration proceeds and retrieve it after it is finished. Currently, you cannot union with the solution set, but a CoGroup could give you the desired result. Alternatively, you might want to look at bulk iterations (Iterate abstraction) [1]. With these you can produce a completely new dataset after every iteration. I hope that helps! -Vasia. [1]: https://ci.apache.org/projects/flink/flink-docs-master/apis/batch/iterations.html On 20 March 2016 at 18:12, Mengqi Yang <melody2014...@gmail.com> wrote: > Hi all, > > Are there any approaches here I could get intermediate solution sets from > every delta iteration? I tried union but the compiler gave me the error: > Exception in thread "main" > org.apache.flink.api.common.InvalidProgramException: Error: The only > operations allowed on the solution set are Join and CoGroup. > > > Best, > Mengqi > > > > -- > View this message in context: > http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Intermediate-solution-set-of-delta-iteration-tp5656.html > Sent from the Apache Flink User Mailing List archive. mailing list archive > at Nabble.com. >
