apache/cassandra · error · InvalidRequestException

Duplicate argument names for given function

Error message

Duplicate argument names for given function %s with argument names %s

What it means

CREATE FUNCTION validation rejects a function whose argument names contain duplicates. Cassandra requires each argument of a user-defined function to have a unique identifier so arguments can be referenced unambiguously (e.g. in language bodies and state functions). The check compares the size of the argument-name set against the list size in CreateFunctionStatement.apply.

Solutions

1. Rename the duplicated argument so every argument name in the signature is unique
2. Review the full argument list in the CREATE FUNCTION statement for accidental repeats
3. If DDL is generated, fix the generator to enforce unique parameter names

Example fix

// before
CREATE FUNCTION ks.f(a int, a text) RETURNS NULL ON NULL INPUT RETURNS int LANGUAGE java AS 'return 0;';
// after
CREATE FUNCTION ks.f(a int, b text) RETURNS NULL ON NULL INPUT RETURNS int LANGUAGE java AS 'return 0;';

Set<String> names = new HashSet<>(argumentNames);
if (names.size() != argumentNames.size()) throw new IllegalArgumentException("Duplicate argument names: " + argumentNames);

boolean hasUniqueArgNames(List<String> names) { return new HashSet<>(names).size() == names.size(); }

try { session.execute(createFunctionStmt); } catch (InvalidRequestException e) { if (e.getMessage().startsWith("Duplicate argument names")) { /* fix signature and retry */ } else throw e; }

When it happens

Trigger: Executing CREATE [OR REPLACE] FUNCTION with two arguments sharing the same declared name, e.g. CREATE FUNCTION f(a int, a text).

Common situations: Copy-pasted function signatures where a parameter name was forgotten to be renamed; generated DDL scripts producing duplicated parameter names; typos that coincidentally match an existing parameter.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• Argument ' ' cannot be frozen; remove frozen<> modifier from
• Return type ' ' cannot be frozen; remove frozen<> modifier…
• Accord transactions are disabled on table (table is being…
• Aggregate name ' ' is invalid
• Argument ' ' cannot be frozen; remove frozen<> modifier from

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/a7baf8374f593cd6. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/cql3/statements/schema/CreateFunctionStatement.java:106

    @Override
    public boolean compatibleWith(ClusterMetadata metadata)
    {
        return metadata.directory.commonSerializationVersion.isAtLeast(Version.V0);
    }

    // TODO: replace affected aggregates !!
    public Keyspaces apply(ClusterMetadata metadata)
    {
        if (ifNotExists && orReplace)
            throw ire("Cannot use both 'OR REPLACE' and 'IF NOT EXISTS' directives");

        UDFunction.assertUdfsEnabled(language);

        if (!FunctionName.isNameValid(functionName))
            throw ire("Function name '%s' is invalid", functionName);

        if (new HashSet<>(argumentNames).size() != argumentNames.size())
            throw ire("Duplicate argument names for given function %s with argument names %s", functionName, argumentNames);

        rawArgumentTypes.stream()
                        .filter(raw -> !raw.isImplicitlyFrozen() && raw.isFrozen())
                        .findFirst()
                        .ifPresent(t -> { throw ire("Argument '%s' cannot be frozen; remove frozen<> modifier from '%s'", t, t); });

        if (!rawReturnType.isImplicitlyFrozen() && rawReturnType.isFrozen())
            throw ire("Return type '%s' cannot be frozen; remove frozen<> modifier from '%s'", rawReturnType, rawReturnType);

        Keyspaces schema = metadata.schema.getKeyspaces();
        KeyspaceMetadata keyspace = schema.getNullable(keyspaceName);
        if (null == keyspace)
            throw ire("Keyspace '%s' doesn't exist", keyspaceName);

        List<AbstractType<?>> argumentTypes =
            rawArgumentTypes.stream()
                            .map(t -> t.prepare(keyspaceName, keyspace.types).getType().udfType())
                            .collect(toList());

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