[jira] [Created] (FLINK-16528) Support Limit push down for streaming sources

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

Jark Wu created FLINK-16528:
-------------------------------

             Summary: Support Limit push down for streaming sources
                 Key: FLINK-16528
                 URL: https://issues.apache.org/jira/browse/FLINK-16528
             Project: Flink
          Issue Type: New Feature
          Components: Table SQL / Ecosystem, Table SQL / Planner
            Reporter: Jark Wu
             Fix For: 1.11.0


Currently, a limit query {{SELECT * FROM kafka LIMIT 10}} will be translated into TopN operator and will scan the full data in the source. However, {{LIMIT}} is a very useful feature in SQL CLI to explore data in the source. It doesn't make sense it never stop. 

We can support such case in streaming mode:
{{code}}
flink > SELECT * FROM kafka LIMIT 10;
     kafka_key      |    user_name    | lang |       created_at
--------------------+-----------------+------+-------------------------
 494227746231685121 | burncaniff      | en   | 2014-07-29 14:07:31.000
 494227746214535169 | gu8tn           | ja   | 2014-07-29 14:07:31.000
 494227746219126785 | pequitamedicen  | es   | 2014-07-29 14:07:31.000
 494227746201931777 | josnyS          | ht   | 2014-07-29 14:07:31.000
 494227746219110401 | Cafe510         | en   | 2014-07-29 14:07:31.000
 494227746210332673 | Da_JuanAnd_Only | en   | 2014-07-29 14:07:31.000
 494227746193956865 | Smile_Kidrauhl6 | pt   | 2014-07-29 14:07:31.000
 494227750426017793 | CashforeverCD   | en   | 2014-07-29 14:07:32.000
 494227750396653569 | FilmArsivimiz   | tr   | 2014-07-29 14:07:32.000
 494227750388256769 | jmolas          | es   | 2014-07-29 14:07:32.000
(10 rows)
{{code}}




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