User-Defined Functions (UDFs)

MonkDB supports SQL-callable UDFs via CREATE FUNCTION.

Lifecycle

Create

CREATE FUNCTION doc.my_add(a INTEGER, b INTEGER)
RETURNS INTEGER
LANGUAGE JAVASCRIPT
AS 'function(a, b) { return a + b; }';

Execute

SELECT doc.my_add(2, 3);

Replace

CREATE OR REPLACE FUNCTION doc.my_add(a INTEGER, b INTEGER)
RETURNS INTEGER
LANGUAGE JAVASCRIPT
AS 'function(a, b) { return a + b + 1; }';

Drop

DROP FUNCTION IF EXISTS doc.my_add(INTEGER, INTEGER);

Operational guidance

• Keep logic deterministic and side-effect free for predictable planning.
• Avoid heavyweight CPU loops in hot query paths.
• Version UDF names/signatures deliberately for safer rollout.
• Track execution patterns through sys.jobs/sys.jobs_log statements.