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https://issues.apache.org/jira/browse/SAMZA-552?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14390955#comment-14390955
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Yi Pan (Data Infrastructure) commented on SAMZA-552:
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[~criccomini], thanks for the comment. As for the API, I separated the APIs
into two sets: one for automatic query layer, and some additional APIs for
standalone operators used by the user directly.
{quote}
I found that requiring both time and offsets in this API are a little confusing.
{quote}
I assume that you were referring to the getMessages() API here. It makes sense
to not mix time and offsets. We can actually only use time in time-based window
and only use offset in tuple-based window. I will make the update to the APIs
here.
> 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)
> Attachments: DESIGN-SAMZA-552-3.md, DESIGN-SAMZA-552-3.pdf,
> DESIGN-SAMZA-552-6.md, DESIGN-SAMZA-552-6.pdf
>
>
> 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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