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https://issues.apache.org/jira/browse/SAMZA-552?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14340622#comment-14340622
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Chris Riccomini commented on SAMZA-552:
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Observation: I also think that what they describe is essentially just a 2 week
sliding window. [~julianhyde] had described sliding windows as having the
property of preserving cardinality between input and output. If you take their
example remove the partial-suppression that they're doing (1 minute stream
time, or watermark move time), you just have a 2 week sliding window. How you
suppress determines the characteristics of the sliding window. You could turn
it into a tumbling window, a hopping window, etc.
> Tuple or time window semantics in physical operator
> ---------------------------------------------------
>
> Key: SAMZA-552
> URL: https://issues.apache.org/jira/browse/SAMZA-552
> Project: Samza
> Issue Type: Sub-task
> Components: sql
> Affects Versions: 0.9.0
> Reporter: Yi Pan (Data Infrastructure)
> Assignee: Yi Pan (Data Infrastructure)
>
> The discussion is based on how to support tuple and/or time based window
> operators in Samza physical operator layer.
> Here are the few observations:
> # Tuple represents the “physical ordering” of events while time-based window
> has semantic meanings to users
> # Total ordering between tuples are possible within Samza/Kafka given a
> deterministic MessageSelector on all input streams and offsets within each
> stream
> # No matter whether tuple or time is used to measure the window size, the
> window termination condition is needed to close a window to avoid the job to
> be wedged forever
> The following questions have to be answered to fully implement a window
> operator:
> # how to determine that a window is closed and no new tuples will be added?
> ## For tuple based, how do we close the window if messages do not come or get
> delayed?
> ## For time based, how do we close the window if
> ### the messages are not strictly in order w/ the time?
> ### the message w/ timestamp greater than the window boundary does not come
> or gets delayed?
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