Function AlterFunction

src/backend/commands/functioncmds.c:1768–2016

* Implements the ALTER FUNCTION utility command (except for the * RENAME and OWNER clauses, which are handled as part of the generic * ALTER framework). */

 * ALTER framework).
 */
ObjectAddress
AlterFunction(ParseState *pstate, AlterFunctionStmt *stmt)
{
	HeapTuple	tup;
	Oid			funcOid;
	Form_pg_proc procForm;
	bool		is_procedure;
	Relation	rel;
	ListCell   *l;
	DefElem    *volatility_item = NULL;
	DefElem    *strict_item = NULL;
	DefElem    *security_def_item = NULL;
	DefElem    *leakproof_item = NULL;
	List	   *set_items = NIL;
	DefElem    *cost_item = NULL;
	DefElem    *rows_item = NULL;
	DefElem    *support_item = NULL;
	DefElem    *parallel_item = NULL;
	ObjectAddress address;
	DefElem    *describe_item = NULL;
	DefElem    *data_access_item = NULL;
	DefElem    *exec_location_item = NULL;
	bool		isnull;
	char		data_access;
	char		exec_location;

	rel = table_open(ProcedureRelationId, RowExclusiveLock);

	funcOid = LookupFuncWithArgs(stmt->objtype, stmt->func, false);

	ObjectAddressSet(address, ProcedureRelationId, funcOid);

	tup = SearchSysCacheCopy1(PROCOID, ObjectIdGetDatum(funcOid));
	if (!HeapTupleIsValid(tup)) /* should not happen */
		elog(ERROR, "cache lookup failed for function %u", funcOid);

	procForm = (Form_pg_proc) GETSTRUCT(tup);

	/* Permission check: must own function */
	if (!pg_proc_ownercheck(funcOid, GetUserId()))
		aclcheck_error(ACLCHECK_NOT_OWNER, stmt->objtype,
					   NameListToString(stmt->func->objname));

	/* check bootstrap object */
	CheckForModifySystemFunc(funcOid, stmt->func->objname);

	if (procForm->prokind == PROKIND_AGGREGATE)
		ereport(ERROR,
				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
				 errmsg("\"%s\" is an aggregate function",
						NameListToString(stmt->func->objname))));

	is_procedure = (procForm->prokind == PROKIND_PROCEDURE);

	/* Examine requested actions. */
	foreach(l, stmt->actions)
	{
		DefElem    *defel = (DefElem *) lfirst(l);