User-Defined Functions

User-defined functions extend the SQL computation capabilities of Lakehouse. Two types are supported: SQL Function (executed within the engine) and External Function (calls an external service).

For a detailed introduction, see Function Object Model.

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In This Chapter

SQL Function

Page	Description
CREATE SQL FUNCTION	Create a SQL scalar function or table function
DROP FUNCTION	Drop a function
DESC FUNCTION	View detailed information about a function
SHOW FUNCTIONS	List all functions (including built-in functions)

External Function

Page	Description
CREATE EXTERNAL FUNCTION	Create a function that calls an external service (Python/Java)
DROP FUNCTION	Drop an external function
SHOW EXTERNAL FUNCTIONS	List all external functions

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Common Operations

-- Create a SQL scalar function CREATE FUNCTION public.area(x DOUBLE, y DOUBLE) RETURNS DOUBLE RETURN x * y; -- Use the function SELECT public.area(3, 4); -- Output: 12.0 -- List all functions SHOW FUNCTIONS; -- Drop a function DROP FUNCTION public.area;

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Related Documentation

Document	Description
Function Object Model	Function type comparison, permission notes, complete examples
External Function Workflow	Complete process from development to deployment
SQL Function Reference	Complete list of built-in functions