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https://issues.apache.org/jira/browse/CALCITE-3272?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17166676#comment-17166676
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Rui Wang commented on CALCITE-3272:
-----------------------------------
Sorry for the confusion I made. I intended to say use a new function named
"current_watermark_timestamp", or "watermark_timestamp".
It's a good idea to start from metadata-driven conditions like "EMIT AFTER
WATERMARK". I think it is something that people have less disagreement so far.
Regarding the implementation though, I believe the underlying implementation
will still convert "EMIT AFTER WATERMARK" to an expression. E.g.
"current_watermark_timestamp() >= window_end". Thus the underlying
implementation could still based on expression evaluations on data.
We can definitely discuss whether we want to expose expressions directly on
EMIT in the future.
> TUMBLE Table-valued Function
> ----------------------------
>
> Key: CALCITE-3272
> URL: https://issues.apache.org/jira/browse/CALCITE-3272
> Project: Calcite
> Issue Type: Sub-task
> Reporter: Rui Wang
> Assignee: Rui Wang
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.22.0
>
> Time Spent: 19h 20m
> Remaining Estimate: 0h
>
> Define a builtin TVF: Tumble (data , timecol , dur, [ offset ])
> The return value of Tumble is a relation that includes all columns of data as
> well as additional event time columns window_start and window_end.
> Examples of TUMBLE TVF are (from https://s.apache.org/streaming-beam-sql ):
> 8:21> SELECT * FROM Bid;
> --------------------------
> | bidtime | price | item |
> --------------------------
> | 8:07 | $2 | A |
> | 8:11 | $3 | B |
> | 8:05 | $4 | C |
> | 8:09 | $5 | D |
> | 8:13 | $1 | E |
> | 8:17 | $6 | F |
> --------------------------
> 8:21> SELECT *
> FROM TABLE Tumble (
> data => TABLE Bid ,
> timecol => DESCRIPTOR ( bidtime ) ,
> dur => INTERVAL '10' MINUTES ,
> offset => INTERVAL '0' MINUTES );
> ------------------------------------------
> | window_start | window_end | bidtime | price | item |
> ------------------------------------------
> | 8:00 | 8:10 | 8:07 | $2 | A |
> | 8:10 | 8:20 | 8:11 | $3 | B |
> | 8:00 | 8:10 | 8:05 | $4 | C |
> | 8:00 | 8:10 | 8:09 | $5 | D |
> | 8:10 | 8:20 | 8:13 | $1 | E |
> | 8:10 | 8:20 | 8:17 | $6 | F |
> ------------------------------------------
> 8:21> SELECT MAX ( window_start ) , window_end , SUM ( price )
> FROM TABLE Tumble (
> data => TABLE ( Bid ) ,
> timecol => DESCRIPTOR ( bidtime ) ,
> dur => INTERVAL '10 ' MINUTES )
> GROUP BY wend;
> -------------------------
> | window_start | window_end | price |
> -------------------------
> | 8:00 | 8:10 | $11 |
> | 8:10 | 8:20 | $10 |
> -------------------------
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