Hi Stephen, Chesney was right, you will have to use a more complex version of the window processing function. Perhaps your goal can be achieve by this specific function with incremental aggregation [1]. If not you can always use the regular process window function [2]. Both of these methods have access to the KEY information you required.
Thanks, Rong [1] https://ci.apache.org/projects/flink/flink-docs-release-1.7/dev/stream/operators/windows.html#processwindowfunction-with-incremental-aggregation [2] https://ci.apache.org/projects/flink/flink-docs-release-1.7/dev/stream/operators/windows.html#processwindowfunction On Sun, Feb 10, 2019 at 11:29 AM Stephen Connolly < stephen.alan.conno...@gmail.com> wrote: > > > On Sun, 10 Feb 2019 at 09:48, Chesnay Schepler <ches...@apache.org> wrote: > >> There are also versions of WindowedStream#aggregate that accept an >> additional WindowFunction/ProcessWindowFunction, which do have access to >> the key via apply()/process() respectively. These functions are called >> post aggregation. >> > > Cool I'll chase those down > > >> >> On 08.02.2019 18:24, stephen.alan.conno...@gmail.com wrote: >> > If I write my aggregation logic as a WindowFunction then I get access >> to the key as the first parameter in WindowFunction.apply(...) however the >> Javadocs for calling WindowedStream.apply(WindowFunction) state: >> > >> >> Note that this function requires that all data in the windows is >> buffered until the window >> >> is evaluated, as the function provides no means of incremental >> aggregation. >> > Which sounds bad. >> > >> > It seems the recommended alternative is to use one of the >> WindowFunction.aggregate(AggregateFunction) however I cannot see how to get >> access to the key... >> > >> > Is my only solution to transform my data into a Tuple if I need access >> to the key post aggregation? >> > >> > Thanks in advance >> > >> > -stephenc >> > >> >>
