[jira] [Commented] (CALCITE-4146) Implement EMIT AFTER WATERMARK

["liupengcheng (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-4146?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17169688#comment-17169688 ] 

liupengcheng commented on CALCITE-4146:
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Would we support other EMIT strategies in the future or only the watermark based strategy? I'm not sure about it.

In reference [1], it proposed two kinds of strategy: periodic delay materialization and the watermark materialization.
Actually, the periodic ways can be replaced by periodic watermark(proctime based). Currently, flink separates window as count window and time window, it handle the materialization for time window with the watermark semantics as I mentioned and it supports creating source table with some extra watermark information.

Here the TUMBLE/HOP/SESSION are time windows? we can make the watermark as the default semantics without the EMIT syntax?

> Implement EMIT AFTER WATERMARK
> ------------------------------
>
>                 Key: CALCITE-4146
>                 URL: https://issues.apache.org/jira/browse/CALCITE-4146
>             Project: Calcite
>          Issue Type: Sub-task
>            Reporter: Rui Wang
>            Assignee: Rui Wang
>            Priority: Major
>
> The goal is to support the following syntax
> {code:sql}
> SELECT clause
> FROM TUMBLE/HOP/SESSION
> EMIT AFTER WATERMARK
> {code}
> note that "EMIT AFTER WATERMARK" is the new thing.
> "EMIT AFTER WATERMARK" is proposed in [1]. This idea proposes a way to allow streaming SQL queries control materialization latency. More specifically, it means emit elements in a window once the watermark passes the end of that window.
> There are more context discussed in [2][3].
> [1]: https://arxiv.org/pdf/1905.12133.pdf
> [2]: https://issues.apache.org/jira/browse/CALCITE-3272?focusedCommentId=17166580&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-17166580
> [3]:https://lists.apache.org/thread.html/r5bd9a6f7af2c0cd81aecd4de512fd889fbf15f112cc3704f188b1d4f%40%3Cdev.calcite.apache.org%3E



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