PostgreSQL too_many_arguments Error (54023) – Causes and Fixes

PostgreSQL error 54023 "too many arguments" - what does it mean and how do I fix it?

What does this error mean?

PostgreSQL returns error 54023 when the supplied parameter count exceeds the number declared in the called object's signature. The object can be a user defined function, a built-in function, an aggregate, an operator, or a procedure.

Because argument positions drive both type resolution and overload selection, the engine refuses to guess which parameters are unintended.

It stops and emits ERROR: too many arguments.

What Causes This Error?

Calling a regular function with extra positional parameters is the most common trigger. Example: SELECT substring('abc',1,1,1); passes four arguments to a three-argument function.

Supplying an extra filter argument to an aggregate or window function, such as COUNT(col, another_col), also raises 54023.

Operator misuse can cause the same error.

Writing BETWEEN x AND y AND z supplies a third operand to a binary operator.

Autogenerated code or ORM helpers that append columns dynamically often inject too many parameters without notice.

How to Fix PostgreSQL error 54023

First, inspect the object's signature with \df+ in psql or by querying pg_catalog.pg_proc to confirm the expected parameter list.

Update your SQL so the call passes exactly the declared number of arguments.

Remove extras or move optional values into DEFAULT parameters if available.

If you legitimately need a variable parameter list, create or replace the function with a VARIADIC parameter or implement an overloaded version that accepts the additional arguments.

For aggregates, build a custom aggregate that matches the desired arity, or consolidate values into an array argument.

Common Scenarios and Solutions

Substring misuse: replace SELECT substring(col,1,3,4) with SELECT substring(col,1,3).

COUNT with multiple columns: use COUNT(*) FILTER (WHERE cond) or COUNT(col) instead of COUNT(col1,col2).

Dynamic IN list: turn SELECT my_func(1,2,3,4) into SELECT my_func(ARRAY[1,2,3,4]) when the function expects an array.

Best Practices to Avoid This Error

Always consult pg_proc or the documentation before calling unfamiliar functions.

Code review queries for argument mismatches.

Adopt naming conventions that differentiate variadic functions (e.g., *_var) from fixed-arity ones.

Use Galaxy's AI copilot to autocomplete function signatures correctly and flag mismatches during editing.

Add automated tests that run pg_stat_statements to detect 54023 occurrences in staging before production deployment.

Related Errors and Solutions

PostgreSQL error 42883 undefined_function appears when the argument types, not the count, prevent a function match.

Error 42804 datatype_mismatch arises when argument types conflict with the signature even though the count is correct.

Error 42P13 insufficient_privilege triggers when calling a function without execute rights, unrelated to argument count.

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