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Flink Jira Bot updated FLINK-5047:
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    Labels: auto-deprioritized-major auto-unassigned pull-request-available 
stale-minor  (was: auto-deprioritized-major auto-unassigned 
pull-request-available)

I am the [Flink Jira Bot|https://github.com/apache/flink-jira-bot/] and I help 
the community manage its development. I see this issues has been marked as 
Minor but is unassigned and neither itself nor its Sub-Tasks have been updated 
for 180 days. I have gone ahead and marked it "stale-minor". If this ticket is 
still Minor, please either assign yourself or give an update. Afterwards, 
please remove the label or in 7 days the issue will be deprioritized.


> Add sliding group-windows for batch tables
> ------------------------------------------
>
>                 Key: FLINK-5047
>                 URL: https://issues.apache.org/jira/browse/FLINK-5047
>             Project: Flink
>          Issue Type: New Feature
>          Components: Table SQL / API
>            Reporter: Jark Wu
>            Priority: Minor
>              Labels: auto-deprioritized-major, auto-unassigned, 
> pull-request-available, stale-minor
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> Add 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].
> There are 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.
> 3. There is also a third, hybrid solution: Doing the pre-aggregation on the 
> largest non-overlapping windows (as in 2) and replicating these results and 
> processing those as in the 1) approach. The benefits of this is that it a) is 
> based on the implementation that supports non-combinable aggregates (which is 
> required in any case) and b) that it does not require the implementation of 
> the SQL WINDOW operator. Internally, this can be implemented again as an 
> optimizer rule that translates the SlidingWindow into a pre-aggregating 
> TublingWindow and a final SlidingWindow (with replication).
> see FLINK-4692 for more discussion



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