Jark Wu created FLINK-16528:
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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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