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https://issues.apache.org/jira/browse/CALCITE-4146?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17170140#comment-17170140
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Rui Wang edited comment on CALCITE-4146 at 8/21/20, 6:04 PM:
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Also, there are also three output mode for EMIT
1. discarding/delta mode. This is like a macro batch system.
2. accumulating mode. This is each emit of the batch all contains all history
data.
3. accumulating and retracting mode. This is the one that retractions will
exist.
in Calcite, EMIT syntax will work with 3. I haven't had an idea whether to
support 1 and 2.
was (Author: amaliujia):
Also, there are also three output mode for EMIT
1. discarding/delta mode. This is like a macro batch system.
2. accumulating mode. This is each emit of the batch all contains all history
data.
3. accumulating and discarding mode. This is the one that retractions will
exist.
in Calcite, EMIT syntax will work with 3. I haven't had an idea whether to
support 1 and 2.
> Implement EMIT Syntax
> ---------------------
>
> Key: CALCITE-4146
> URL: https://issues.apache.org/jira/browse/CALCITE-4146
> Project: Calcite
> Issue Type: New Feature
> 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]
> {code}
> EMIT Syntax is proposed in [One SQL to Rule Them
> All|https://arxiv.org/pdf/1905.12133.pdf]. This idea proposes a way to allow
> streaming SQL queries control materialization latency.
> Regarding the types of emit strategies, due to limit pages, that paper only
> lists two strategies, and Calcite should support at least four categories:
> # Event time triggers. Emitting depends on the relationship between
> watermark and event timestamp of events. Handling late data is also included
> in this category.
> # Processing time triggers. Emitting depends on the system clock. This is
> a natural idea of emitting. E.g. emit the current result every hour without
> considering if data in a window is already complete.
> # data-driven triggers. E.g. emit when accumulated events exceed a
> threshold (e.g. emit when have acculucated 1000 events)
> # Composite triggers. There is a need to concat 1, 2, 3 by OR and AND to
> achieve better latency control.
> There are more context discussed in
> [CALCITE-3272|https://issues.apache.org/jira/browse/CALCITE-3272?focusedCommentId=17166580&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-17166580]
> and the [EMIT syntax proposal for event-timestamp semantic
> windowing|https://lists.apache.org/thread.html/r5bd9a6f7af2c0cd81aecd4de512fd889fbf15f112cc3704f188b1d4f%40%3Cdev.calcite.apache.org%3E]
> email thread.
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