User-Defined Functions
This documentation is for an unreleased version of Apache Flink. We recommend you use the latest stable version.

User-Defined Functions #

Flink SQL supports user-defined functions (UDFs) to extend the built-in functionality. You can create custom scalar functions, table functions, and aggregate functions to use in your SQL queries.

Registering UDFs in SQL #

Once you have developed a UDF, you can register it in SQL using the CREATE FUNCTION statement:

CREATE FUNCTION myudf AS 'com.example.MyScalarFunction';

See the CREATE FUNCTION documentation for the full syntax.

Developing UDFs #

Writing user-defined functions requires Java, Scala, or Python programming. For detailed information on how to develop UDFs, see the Table API documentation:

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