apache/cassandra · error · InvalidRequestException

Final function doesn't exist

Error message

Final function %s doesn't exist

What it means

Thrown by CreateAggregateStatement.apply when a CREATE AGGREGATE statement names a FINALFUNC that does not exist in the target keyspace with a signature of exactly one argument of the aggregate's state type. Cassandra resolves the final function during schema application and refuses to create the aggregate if it cannot be found.

Solutions

1. Create the missing scalar function first: CREATE FUNCTION <ks>.<finalfunc>(state <stateType>) RETURNS NULL ON NULL INPUT ...
2. Verify the final function's argument type exactly matches the aggregate's STYPE.
3. Check you are in the same keyspace (or fully qualify the function name with the keyspace).
4. If the aggregate needs no final transformation, drop the FINALFUNC clause entirely.

Example fix

// before
CREATE AGGREGATE ks.avg(int) SFUNC avg_state STYPE avg_state FINALFUNC divide_by_count;
// (divide_by_count(int) does not exist)
// after
CREATE FUNCTION ks.divide_by_count(total avg_state) RETURNS NULL ON NULL INPUT RETURNS int ...;
CREATE AGGREGATE ks.avg(int) SFUNC avg_state STYPE avg_state FINALFUNC divide_by_count;

// pseudocode before CREATE AGGREGATE
var finalFunc = keyspace.userFunctions.find(finalFuncName, List.of(stateType));
if (finalFunc.isEmpty()) throw new IllegalStateException(
    "FINALFUNC " + finalFuncName + "(" + stateType + ") not found in keyspace " + keyspace);

// catch InvalidRequestException from session.execute
try { session.execute(ddl); }
catch (InvalidRequestException e) {
    if (e.getMessage().contains("doesn't exist")) { /* create the final function, then retry */ }
    else throw e;
}

When it happens

Trigger: CREATE AGGREGATE ... FINALFUNC <name> where no user-defined scalar function of that name accepting a single argument of the state type exists in the keyspace (or the function exists but with a different argument type).

Common situations: Typo in the final function name; final function created in a different keyspace than the aggregate; final function declared with a parameter type that differs from the state type; FINALFUNC created after the aggregate was attempted.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

• Final function isn't a scalar function
• ACCESS TO DATACENTERS operations not supported by…
• Aggregate ' ' already exists
• Aggregate ' ' cannot replace a function
• Argument ' ' cannot be frozen; remove frozen<> modifier from

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/278d9d3958c82b59. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/cql3/statements/schema/CreateAggregateStatement.java:160

        if (!stateFunction.returnType().equals(stateType))
        {
            throw ire("State function %s return type must be the same as the first argument type - check STYPE, argument and return types",
                      stateFunctionString());
        }

        /*
         * Resolve the final function and return type
         */

        UserFunction finalFunction = null;
        AbstractType<?> returnType = stateFunction.returnType();

        if (null != finalFunctionName)
        {
            finalFunction = keyspace.userFunctions.find(finalFunctionName, singletonList(stateType)).orElse(null);
            if (null == finalFunction)
                throw ire("Final function %s doesn't exist", finalFunctionString());

            if (finalFunction.isAggregate())
                throw ire("Final function %s isn't a scalar function", finalFunctionString());

            // override return type with that of the final function
            returnType = finalFunction.returnType();
        }

        /*
         * Validate initial condition
         */

        ByteBuffer initialValue = null;
        if (null != rawInitialValue)
        {
            String term = rawInitialValue.toString();
            initialValue = Term.asBytes(keyspaceName, term, stateType);

View on GitHub (pinned to 88fd0f6a0e)