apache/cassandra · error · InvalidRequestException

Ambiguous call to function %s (can be matched by following s

Error message

Ambiguous call to function %s (can be matched by following signatures: %s): use type casts to disambiguate

What it means

The generic ambiguity error of FunctionResolver: more than one function overload (compatibles) matched the provided argument types, no receiver type narrows it, and it isn't an operator/negation case. Cassandra lists all matching signatures and asks for explicit type casts to disambiguate rather than guessing.

Source

Thrown at src/java/org/apache/cassandra/cql3/functions/FunctionResolver.java:187

            if (OperationFcts.isOperation(name))
            {
                if (receiverType != null && !containsMarkers(providedArgs))
                {
                    for (Function toTest : compatibles)
                    {
                        List<AbstractType<?>> argTypes = toTest.argTypes();
                        if (receiverType.equals(argTypes.get(0)) && receiverType.equals(argTypes.get(1)))
                            return toTest;
                    }
                }
                throw invalidRequest("Ambiguous '%s' operation with args %s and %s: use type hint to disambiguate, example '(int) ?'",
                                     OperationFcts.getOperator(name), providedArgs.get(0), providedArgs.get(1));
            }

            if (OperationFcts.isNegation(name))
                throw invalidRequest("Ambiguous negation: use type casts to disambiguate");

            throw invalidRequest("Ambiguous call to function %s (can be matched by following signatures: %s): use type casts to disambiguate",
                                 name, format(compatibles));
        }

        return compatibles.get(0);
    }

    /**
     * Checks if at least one of the specified arguments is a marker.
     *
     * @param args the arguments to check
     * @return {@code true} if if at least one of the specified arguments is a marker, {@code false} otherwise
     */
    private static boolean containsMarkers(List<? extends AssignmentTestable> args)
    {
        return args.stream().anyMatch(Marker.Raw.class::isInstance);
    }

    /**

View on GitHub (pinned to 88fd0f6a0e)

Solutions

Add explicit casts to the arguments so only one signature matches: f((int)1, (int)2)
Drop or rename the redundant UDF overload that created the ambiguity (DROP FUNCTION)
Inspect the signature list in the message and pick the intended one, casting accordingly
Where possible, pass typed columns/literals whose types exactly match one overload

Example fix

// before: matches both (int,int) and (float,float) overloads
SELECT myfun(1, 2) FROM t;
// after
datastax session.execute("SELECT myfun((int)1, (int)2) FROM t");

Defensive patterns

Strategy: validation

Validate before calling

// before creating a new UDF overload, check for coercible overlap
// SELECT function_name, argument_types FROM system_schema.functions WHERE keyspace_name = 'ks' AND function_name = 'myfun';

Prevention

Avoid registering UDF overloads with mutually coercible parameter types
Cast literal arguments to exact overload types in generated queries
Review the signature list in the error to identify overlapping overloads

When it happens

Trigger: Calling an overloaded native function (e.g. min/max/dateFloor-ish family, or a UDF registered with several overloads) with argument types that match 2+ signatures, e.g. a UDF overloaded for (int,int) and (float,float) called with two literals like f(1, 2) that can coerce either way.

Common situations: UDFs defined multiple times with coercibly-compatible parameter types; calls with untyped literals that fit several overloads; after adding a new overload that now overlaps an existing one.

Understand the failure class

Background: "must be a positive integer", "cannot be empty", "invalid argument": how invalid-argument errors work across open-source libraries — this error's family across 33 libraries.

Related errors

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/f222485271baab23. Report an issue: GitHub.