On Thu, Nov 21, 2019 at 10:32 AM Reuven Lax <[email protected]> wrote:
>
> In particular, since windows can be data based (e.g. session windows) the set 
> of windows is not always knowable in advance.

It's [IntervalWindow(start, end) for start in range(MIN_TIMESTAMP,
MAX_TIMESTAMP) for end in range(MIN_TIMESTAMP, MAX_TIMESTAMP) if start
< end], though admittedly most have no data :) The statement is,
however, true in general.

> On Thu, Nov 21, 2019 at 10:29 AM Robert Bradshaw <[email protected]> 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 <[email protected]> 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

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