1959
MySQLERRORCommonStored RoutinesHIGH confidence
AGGREGATE is not supported for stored functions
Production Risk
None — function creation is rejected.
What this means
The AGGREGATE keyword was specified in a CREATE FUNCTION statement, but MySQL does not support user-defined aggregate stored functions using this syntax. Aggregate functions require a different mechanism (loadable plugins in MySQL 8.0).
Why it happens
- 1CREATE AGGREGATE FUNCTION using the stored function syntax instead of a UDF plugin.
How to reproduce
trigger — this will error
trigger — this will error
CREATE AGGREGATE FUNCTION my_sum(val DOUBLE) RETURNS DOUBLE BEGIN ... END;
expected output
ERROR 1959 (HY000): AGGREGATE is not supported for stored functions.
Fix 1
Use a window function or GROUP BY with a built-in aggregate instead
Use a window function or GROUP BY with a built-in aggregate instead
SELECT SUM(val) FROM t GROUP BY category;
Why this works
Built-in aggregate functions (SUM, AVG, COUNT) cover most use cases.
Fix 2
Implement aggregate UDFs as loadable plugin functions (MySQL 8.0)
Implement aggregate UDFs as loadable plugin functions (MySQL 8.0)
-- Implement as a C++ plugin and install with CREATE FUNCTION ... SONAME
Why this works
True user-defined aggregates require writing a plugin in C++.
Version notes
Sources
Official documentation ↗
MySQL 8.0 — 1959 ER_SP_NO_AGGREGATE
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