Function LookupFuncName

src/backend/parser/parse_func.c:2198–2243

* LookupFuncName * * Given a possibly-qualified function name and optionally a set of argument * types, look up the function. Pass nargs == -1 to indicate that the number * and types of the arguments are unspecified (this is NOT the same as * specifying that there are no arguments). * * If the function name is not schema-qualified, it is sought in the current * namespace search path. *

 * aggregates or window functions here.)
 */
Oid
LookupFuncName(List *funcname, int nargs, const Oid *argtypes, bool missing_ok)
{
	Oid			funcoid;
	FuncLookupError lookupError;

	funcoid = LookupFuncNameInternal(OBJECT_FUNCTION,
									 funcname, nargs, argtypes,
									 false, missing_ok,
									 &lookupError);

	if (OidIsValid(funcoid))
		return funcoid;

	switch (lookupError)
	{
		case FUNCLOOKUP_NOSUCHFUNC:
			/* Let the caller deal with it when missing_ok is true */
			if (missing_ok)
				return InvalidOid;

			if (nargs < 0)
				ereport(ERROR,
						(errcode(ERRCODE_UNDEFINED_FUNCTION),
						 errmsg("could not find a function named \"%s\"",
								NameListToString(funcname))));
			else
				ereport(ERROR,
						(errcode(ERRCODE_UNDEFINED_FUNCTION),
						 errmsg("function %s does not exist",
								func_signature_string(funcname, nargs,
													  NIL, argtypes))));
			break;

		case FUNCLOOKUP_AMBIGUOUS:
			/* Raise an error regardless of missing_ok */
			ereport(ERROR,
					(errcode(ERRCODE_AMBIGUOUS_FUNCTION),
					 errmsg("function name \"%s\" is not unique",
							NameListToString(funcname)),
					 errhint("Specify the argument list to select the function unambiguously.")));
			break;
	}

	return InvalidOid;			/* Keep compiler quiet */
}

/*
 * LookupFuncWithArgs