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Need fill group results for streaming windowing aggregation in case no events #458

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tingfirst opened this issue Dec 30, 2023 · 4 comments · May be fixed by #464
Open

Need fill group results for streaming windowing aggregation in case no events #458

tingfirst opened this issue Dec 30, 2023 · 4 comments · May be fixed by #464
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@yl-lisen
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@tingfirst
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Use case
When there is no event during specific window, current behavior of Proton can't emit that window. It ends up a bit weird semantic results.

Describe the solution you'd like
Take reference from ClickHouse: https://clickhouse.com/blog/working-with-time-series-data-and-functions-ClickHouse

Describe alternatives you've considered

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@tingfirst
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@yl-lisen @chenziliang as we talked, that's a bit urgent issue we need fix.

@gangtao fyi

@yl-lisen
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This is a topic that has been discussed many times:

  1. Fill the default window with default values (which may not be reasonable for some aggregate results (avg/sum/...) unless the user explicitly specifies
  2. Compare Clickhouse's syntax of order by with fill step，it's not good for our streaming window aggr query, since order by is not well supported in streaming queries

For 1) means we don't enable this behavior by default.
For 2) we need use a settings fill_default_window_for_aggr=true or support EMIT DEAFULT WINDOWS , any suggests?

@tingfirst
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  1. yes it should be not enabled by default
  2. For our current stage (quick fix), either setting is okay. l prefer "fill_default_window_for_aggr=true" , which can enable emit default windows (tumbling and hopping only) even without any event, and make aggr functions return 0

Can we make a quick fix asap? I need this quite urgently .

@chenziliang
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chenziliang commented Dec 31, 2023 •
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We don't need order window to fill since we emit in window order already. Setting is a quick / hack way to implement this support. We can think about SQL clause like "EMIT WITH FILL WINDOW" to enable this feature ?

@yl-lisen yl-lisen linked a pull request Dec 31, 2023 that will close this issue
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Feature/support fill missing aggr windows timeplus-io/proton
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@chenziliang @tingfirst @yl-lisen