On Thu, Nov 21, 2019 at 2:46 PM Reuven Lax <re...@google.com> wrote: > > That is racy. It could also be that the side input hasn't been computed yet > but will be available in a second.
It's no more racy than any other side input lookup (as we still respect not declaring a window is empty until the watermark asserts so). > On Thu, Nov 21, 2019 at 2:37 PM Kenneth Knowles <k...@apache.org> wrote: >> >> It can work in pull mode when it is a side input, via >> Combine.globally().asSingletonView(). Then the default is produced when the >> side input is requested and there is no data found. >> >> Kenn >> >> On Thu, Nov 21, 2019 at 10:32 AM Reuven Lax <re...@google.com> wrote: >>> >>> 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
