[jira] [Commented] (SAMZA-552) Tuple or time window semantics in physical operator

["Yi Pan (Data Infrastructure) (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SAMZA-552?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14313242#comment-14313242 ] 

Yi Pan (Data Infrastructure) commented on SAMZA-552:
----------------------------------------------------

Some reference:
http://cs.brown.edu/~ugur/streamsql.pdf

And one more question: how do we support the specification of the window termination condition? In SQL grammar extension or some system config?

> 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)
>
> 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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