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Description

Error 42P13 indicates an issue with the syntax or structure of a `CREATE FUNCTION` statement in PostgreSQL. It typically occurs when the database system cannot parse or understand the function's definition due to a syntax error, incorrect parameters, or an underlying access rule violation.

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Error Message

invalid function definition

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Known Causes

3 known causes

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Incorrect Function Syntax

The `CREATE FUNCTION` statement contains syntax errors, such as missing keywords, incorrect punctuation, or malformed expressions, preventing PostgreSQL from parsing it.

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Mismatched Language or Signature

The specified function language (e.g., PL/pgSQL, SQL) does not match the function body, or there's a mismatch in the number or types of parameters or the return value.

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Insufficient Privileges

The user attempting to create the function lacks the necessary permissions (e.g., `CREATE` privilege on the schema, `USAGE` on languages) to define it.

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Solutions

4 solutions available

1. Check Function Argument Data Types easy

Ensure all function arguments have correctly defined and matching data types.

1

Review the `CREATE FUNCTION` or `ALTER FUNCTION` statement that defines the function causing the error.

2

Verify that each argument in the function definition has a valid PostgreSQL data type (e.g., `INT`, `VARCHAR`, `TIMESTAMP`, `JSONB`).

SELECT proname, proargtypes FROM pg_proc WHERE proname = 'your_function_name';

3

If you are calling the function, ensure that the data types of the values you are passing match the declared argument types of the function.

-- Example: If function expects INT, don't pass a string without casting
-- Incorrect: SELECT your_function_name('123');
-- Correct: SELECT your_function_name(CAST('123' AS INT));

2. Validate Function Return Type easy

Confirm that the declared return type of the function is valid and accurately reflects the function's output.

1

Examine the `RETURNS` clause in your `CREATE FUNCTION` or `ALTER FUNCTION` statement.

2

Ensure the specified return type is a valid PostgreSQL data type.

SELECT proname, prorettype FROM pg_proc WHERE proname = 'your_function_name';

3

If the function uses `RETURN QUERY` or `RETURN NEXT`, ensure the query or values being returned are compatible with the declared return type.

-- Example: If RETURNS SETOF INT, ensure the query returns integer values.
-- Incorrect: CREATE FUNCTION my_func() RETURNS SETOF INT AS $$
-- BEGIN RETURN QUERY SELECT 'hello'; END;
-- $$
-- Correct: CREATE FUNCTION my_func() RETURNS SETOF INT AS $$
-- BEGIN RETURN QUERY SELECT 123;
-- END;
-- $$;

3. Correct Syntax for Function Body medium

Fix any syntax errors within the function's procedural language body (e.g., PL/pgSQL).

1

Carefully inspect the code within the function's body (between `$$` or single quotes).

2

Pay close attention to keywords, semicolons, variable declarations, control flow statements (IF, LOOP), and SQL commands.

-- Example of a common PL/pgSQL syntax error:
-- Incorrect:
-- CREATE FUNCTION my_func() RETURNS INT AS $$
-- DECLARE
--   my_var INT;
-- BEGIN
--   my_var := 5
--   RETURN my_var;
-- END;
-- $$;

-- Correct:
-- CREATE FUNCTION my_func() RETURNS INT AS $$
-- DECLARE
--   my_var INT;
-- BEGIN
--   my_var := 5;
--   RETURN my_var;
-- END;
-- $$;

3

If using `LANGUAGE sql`, ensure the SQL statement is valid on its own.

-- Example for LANGUAGE sql:
-- Incorrect:
-- CREATE FUNCTION my_sql_func() RETURNS INT AS $$
-- SELECT COUNT(*) FROM non_existent_table;
-- $$ LANGUAGE sql;

-- Correct:
-- CREATE FUNCTION my_sql_func() RETURNS INT AS $$
-- SELECT COUNT(*) FROM existing_table;
-- $$ LANGUAGE sql;

4. Recreate the Function with Correct Syntax medium

Drop and recreate the function after identifying and correcting the definition issues.

1

Identify the exact `CREATE FUNCTION` statement that is failing.

2

Drop the existing function.

DROP FUNCTION your_function_name(argument_data_types);

3

Correct any identified syntax errors, data type mismatches, or return type issues in the function definition.

4

Recreate the function with the corrected definition.

-- Example of corrected function definition
CREATE OR REPLACE FUNCTION your_function_name(arg1 INT, arg2 VARCHAR) RETURNS BOOLEAN AS $$
DECLARE
  result BOOLEAN;
BEGIN
  IF arg1 > 10 THEN
    result := TRUE;
  ELSE
    result := FALSE;
  END IF;
  RETURN result;
END;
$$ LANGUAGE plpgsql;

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Related Errors

5 related errors

PostgreSQL Error 42P13: Invalid Function Definition