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https://issues.apache.org/jira/browse/FLINK-6810?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Xingcan Cui updated FLINK-6810:
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Attachment: how to add a scalar function.png
> Add Some built-in Scalar Function supported
> -------------------------------------------
>
> Key: FLINK-6810
> URL: https://issues.apache.org/jira/browse/FLINK-6810
> Project: Flink
> Issue Type: New Feature
> Components: Table API & SQL
> Affects Versions: 1.4.0
> Reporter: sunjincheng
> Assignee: sunjincheng
> Priority: Major
> Labels: starter
> Attachments: how to add a scalar function.png
>
>
> In this JIRA, we will create some sub-tasks for adding specific scalar
> functions such as mathematical-function {{LOG}}, date-functions
> {{DATEADD}}, string-functions {{LPAD}}, etc.
> *How to contribute a build-in scalar function*
> Thank you very much for contributing a build-in function. In order to make
> sure your contributions are in a good direction, it is recommended to read
> the following instructions.
> # Research the behavior of the function that you are going to contribute in
> major DBMSs. This is very important since we have to understand the exact
> semantics of the function.
> # It is recommended to add function for both sql and table-api (Java and
> Scala).
> # For every scalar function, add corresponding docs which should include a
> SQL, a Java and a Scala version in {{./docs/dev/table/functions.md}}. Make
> sure your description of the function is accurate. Please do not copy
> documentation from other projects. Especially if other projects are not
> Apache licensed.
> # Take overflow, NullPointerException and other exceptions into
> consideration.
> # Add unit tests for every new function and its supported APIs. Have a look
> at {{ScalarFunctionsTest}} for how to implement function tests.
> Welcome anybody to add the sub-task about standard database scalar function.
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