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From "Fabian Hueske (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-4692) Add tumbling and sliding group-windows for batch tables
Date Wed, 09 Nov 2016 21:18:58 GMT

    [ https://issues.apache.org/jira/browse/FLINK-4692?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15652063#comment-15652063
] 

Fabian Hueske commented on FLINK-4692:
--------------------------------------

Hi [~jark], I see two ways to implement sliding windows for batch:

1. replicate the output in order to assign keys for overlapping windows. This is probably
the more straight-forward implementation and supports any aggregation function but blows up
the data volume.
2. if the aggregation functions are combinable / pre-aggregatable, we can also find the largest
tumbling window size from which the sliding windows can be assembled. This is basically the
technique used to express sliding windows with plain SQL (GROUP BY + OVER clauses). For a
sliding window {{Slide(10 minutes, 2 minutes)}} this would mean to first compute aggregates
of non-overlapping (tumbling) 2 minute windows and assembling consecutively 5 of these into
a sliding window (could be done in a MapPartition with sorted input). The implementation could
be done as an optimizer rule to split the sliding aggregate into a tumbling aggregate and
a SQL WINDOW operator. Maybe it makes sense to implement the WINDOW clause first and reuse
this for sliding windows.

OK, given the complexity for sliding group-windows, I think it makes sense to split this issue
into tumbling and sliding windows.
What do you think [~jark]?

> Add tumbling and sliding group-windows for batch tables
> -------------------------------------------------------
>
>                 Key: FLINK-4692
>                 URL: https://issues.apache.org/jira/browse/FLINK-4692
>             Project: Flink
>          Issue Type: Sub-task
>          Components: Table API & SQL
>            Reporter: Timo Walther
>
> Add Tumble and Slide group-windows for batch tables as described in [FLIP-11|https://cwiki.apache.org/confluence/display/FLINK/FLIP-11%3A+Table+API+Stream+Aggregations].




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