In particular, since windows can be data based (e.g. session windows) the set of windows is not always knowable in advance.
On Thu, Nov 21, 2019 at 10:29 AM Robert Bradshaw <rober...@google.com> wrote: > The semantics are a bit undefined--the sane extension of the model to > support this is that the default value would show up in every window > (otherwise which window would the default value belong to), but we > don't have support for enumerating windows (or truncating infinite > collections in batch mode). > > On Thu, Nov 21, 2019 at 4:55 AM Robin Qiu <robi...@google.com> wrote: > > > > Hi all, > > > > When I run a Combine.globally() transform with a default value set, on a > PCollection windowed by a FixedWindow, I got this error message: > > > > java.lang.IllegalStateException: Default values are not supported in > Combine.globally() if the input PCollection is not windowed by > GlobalWindows ... > > (from here) > > > > Is this unsupported because it is not implemented yet, or is this a > design decision to not support default values with windows other than > GlobalWIndow (e.g. because the semantics is not well defined)? Where can I > learn more about this? > > > > Best, > > Robin >
