prestodb/presto · error · PrestoException

GENERIC_USER_ERROR

GENERIC_USER_ERROR

Error message

SHOW CREATE FUNCTION is only supported for SQL functions

What it means

The matched function is not a SqlInvokedFunction (SQL-language CREATE FUNCTION), so Presto cannot produce CREATE FUNCTION DDL for it. SHOW CREATE FUNCTION only supports user-defined SQL functions; built-in/native or connector-provided functions have no SQL body to render, hence GENERIC_USER_ERROR.

Source

Thrown at presto-main-base/src/main/java/com/facebook/presto/sql/rewrite/ShowQueriesRewrite.java:666

            QualifiedObjectName functionName = metadata.getFunctionAndTypeManager().getFunctionAndTypeResolver().qualifyObjectName(node.getName());
            Collection<? extends SqlFunction> functions = metadata.getFunctionAndTypeManager().getFunctions(session, functionName);
            if (node.getParameterTypes().isPresent()) {
                List<TypeSignature> parameterTypes = node.getParameterTypes().get().stream()
                        .map(TypeSignature::parseTypeSignature)
                        .collect(toImmutableList());
                functions = functions.stream()
                        .filter(function -> function.getSignature().getArgumentTypes().equals(parameterTypes))
                        .collect(toImmutableList());
            }
            if (functions.isEmpty()) {
                String types = node.getParameterTypes().map(parameterTypes -> format("(%s)", Joiner.on(", ").join(parameterTypes))).orElse("");
                throw new PrestoException(FUNCTION_NOT_FOUND, format("Function not found: %s%s", functionName, types));
            }

            ImmutableList.Builder<Expression> rows = ImmutableList.builder();
            for (SqlFunction function : functions) {
                if (!(function instanceof SqlInvokedFunction)) {
                    throw new PrestoException(GENERIC_USER_ERROR, "SHOW CREATE FUNCTION is only supported for SQL functions");
                }

                SqlInvokedFunction sqlFunction = (SqlInvokedFunction) function;
                boolean temporary = sqlFunction.getFunctionId().getFunctionName().getCatalogSchemaName().equals(SESSION_NAMESPACE);
                CreateFunction createFunction = new CreateFunction(
                        node.getName(),
                        false,
                        temporary,
                        sqlFunction.getParameters().stream()
                                .map(parameter -> new SqlParameterDeclaration(new Identifier(parameter.getName()), parameter.getType().toString()))
                                .collect(toImmutableList()),
                        sqlFunction.getSignature().getReturnType().toString(),
                        Optional.of(sqlFunction.getDescription()),
                        new RoutineCharacteristics(
                                new Language(sqlFunction.getRoutineCharacteristics().getLanguage().getLanguage()),
                                Determinism.valueOf(sqlFunction.getRoutineCharacteristics().getDeterminism().name()),
                                NullCallClause.valueOf(sqlFunction.getRoutineCharacteristics().getNullCallClause().name())),
                        sqlParser.createReturn(sqlFunction.getBody(), createParsingOptions(session, warningCollector)));

View on GitHub (pinned to 55bb57d202)

Solutions

1. Use SHOW FUNCTIONS or documentation to inspect built-ins; their source is not retrievable via SQL
2. Only run SHOW CREATE FUNCTION against functions you created with CREATE FUNCTION
3. Check the function kind column in SHOW FUNCTIONS output before attempting the statement

Example fix

// before
SHOW CREATE FUNCTION abs(double)   -- built-in, native
// after
SHOW CREATE FUNCTION my_schema.safe_div(double, double)  -- SQL UDF

-- 'SQL' in routine_body indicates a SHOW CREATE FUNCTION candidate
SELECT routine_name, routine_body, function_type FROM information_schema.functions
WHERE routine_name = 'safe_div';

try { session.execute("SHOW CREATE FUNCTION " + name); } catch (PrestoException e) { if (e.getErrorCode() == GENERIC_USER_ERROR.toErrorCode()) { /* use SHOW FUNCTIONS / docs for native functions */ } throw e; }

When it happens

Trigger: SHOW CREATE FUNCTION on a built-in function (e.g. abs, max) or any function implemented in Java rather than declared via CREATE FUNCTION.

Common situations: Trying to inspect built-in function definitions; plugins registering native functions the user assumed were SQL functions; session functions vs catalog functions confusion.

Related errors

• SHOW CREATE only supported for tables and views
• INVALID_TABLE_PROPERTY
• NOT_SUPPORTED
• Result set type must be TYPE_FORWARD_ONLY
• Result set concurrency must be CONCUR_READ_ONLY

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/8808e8cac5893f9a. Report an issue: GitHub.