ALTER FUNCTION

Introduced or updated: v1.2.955

Replaces the definition of an existing external function.

Syntax

ALTER FUNCTION <function_name>
    ( <input_param_types> ) RETURNS <return_type> LANGUAGE <language_name>
    HANDLER = '<handler_name>' ADDRESS = '<udf_server_address>'
    [ EXTERNAL_ACCESS_INTEGRATIONS = (<integration_name>, ...) ]
    [ DESC = '<description>' ]

The statement supplies a complete definition. It is not a partial update. For parameter descriptions, see CREATE FUNCTION. ALTER FUNCTION does not support IF EXISTS or IF NOT EXISTS.

Access Control and Policy

Altering a UDF requires the existing global ALTER privilege. When the new definition names integrations, the author also needs USAGE on every integration. The statement does not gain a new SUPER requirement from the integrations.

Every named integration must exist and be enabled. The address must pass the rules and any nonempty operator udf_server_allow_list. Databend checks privileges before integration-bound policy and remote schema validation. Arrow Flight schema requirements remain unchanged.

Omitting EXTERNAL_ACCESS_INTEGRATIONS removes the binding from the new definition and uses the legacy config allow-list path. An empty config list rejects that path. To keep the binding, include it again in the replacement definition.

Example

Assume gcd exists, integration udf_access allows the destination, and the Flight server exposes a compatible gcd_new handler:

ALTER FUNCTION gcd (INT, INT)
    RETURNS INT NULL
    LANGUAGE python
    HANDLER = 'gcd_new'
    ADDRESS = 'https://udf.example.com'
    EXTERNAL_ACCESS_INTEGRATIONS = (udf_access);

For setup and propagation behavior, see External Access Integrations.