Github user balidani commented on the pull request: https://github.com/apache/flink/pull/408#issuecomment-75546102 Hi @vasia! Thanks for the review! I started making the changed, but I got stuck. I get an exception about `GatherUdf` not being Serializable. I tried copying from `VertexCentricIteration` and I'm not sure what's the difference that causes the exception. Here is the full stack trace: https://gist.github.com/balidani/e6f716d3562d2aa131fb Here is `GatherSumApplyIteration.java`: https://gist.github.com/balidani/1139eddcb1b4cbf60404 The GatherUdf is at the end. I didn't bother fully converting the Sum and Apply UDFs, because I already get an exception for gather. What exactly is `ResultTypeQueryable`? Does it have anything to do with Serializability? Should we implement this with all UDFs, just like in `VertexCentricIteration`? Cheers!
--- If your project is set up for it, you can reply to this email and have your reply appear on GitHub as well. If your project does not have this feature enabled and wishes so, or if the feature is enabled but not working, please contact infrastructure at infrastruct...@apache.org or file a JIRA ticket with INFRA. ---