CREATE FUNCTION

Function

To create a catalog function with a catalog and a database namespace, you will need to specify an identifier. You can specify a language tag. You cannot register the function if a function with the same name has already been registered in the catalog. If the language tag is JAVA or SCALA, the identifier is the fully qualified name of the UDF implementation class.

For details about how to create a UDF, see UDFs.

Syntax

CREATE [TEMPORARY|TEMPORARY SYSTEM] FUNCTION
  [IF NOT EXISTS] [[catalog_name.]db_name.]function_name
  AS identifier [LANGUAGE JAVA|SCALA]

Description

TEMPORARY

Create a temporary catalog function with catalogs and database namespaces and overwrite the original catalog function.

TEMPORARY SYSTEM

Create a temporary system catalog function without database namespaces and overwrite the system's built-in functions.

IF NOT EXISTS

If the function already exists, nothing happens.

LANGUAGE JAVA|SCALA

The language tag is used to instruct Flink runtime how to execute the function. Currently, only JAVA and SCALA language tags are supported, and the default language for a function is JAVA.

Example

Create a function named STRINGBACK.

create function STRINGBACK as 'com.dli.StringBack'