AlterForeignServer(AlterForeignServerStmt *stmt)
{
	Relation	rel;
	HeapTuple	tp;
	Datum		repl_val[Natts_pg_foreign_server];
	bool		repl_null[Natts_pg_foreign_server];
	bool		repl_repl[Natts_pg_foreign_server];
	Oid			srvId;
	Form_pg_foreign_server srvForm;
	ObjectAddress address;

	rel = table_open(ForeignServerRelationId, RowExclusiveLock);

	tp = SearchSysCacheCopy1(FOREIGNSERVERNAME,
							 CStringGetDatum(stmt->servername));

	if (!HeapTupleIsValid(tp))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("server \"%s\" does not exist", stmt->servername)));

	srvForm = (Form_pg_foreign_server) GETSTRUCT(tp);
	srvId = srvForm->oid;

	/*
	 * Only owner or a superuser can ALTER a SERVER.
	 */
	if (!pg_foreign_server_ownercheck(srvId, GetUserId()))
		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_FOREIGN_SERVER,
					   stmt->servername);

	memset(repl_val, 0, sizeof(repl_val));
	memset(repl_null, false, sizeof(repl_null));
	memset(repl_repl, false, sizeof(repl_repl));

	if (stmt->has_version)
	{
		/*
		 * Change the server VERSION string.
		 */
		if (stmt->version)
			repl_val[Anum_pg_foreign_server_srvversion - 1] =
				CStringGetTextDatum(stmt->version);
		else
			repl_null[Anum_pg_foreign_server_srvversion - 1] = true;

		repl_repl[Anum_pg_foreign_server_srvversion - 1] = true;
	}

	if (stmt->options)
	{
		ForeignDataWrapper *fdw = GetForeignDataWrapper(srvForm->srvfdw);
		Datum		datum;
		bool		isnull;

		/* Extract the current srvoptions */
		datum = SysCacheGetAttr(FOREIGNSERVEROID,
								tp,
								Anum_pg_foreign_server_srvoptions,
								&isnull);
		if (isnull)
			datum = PointerGetDatum(NULL);

		/* Prepare the options array */
		datum = transformGenericOptions(ForeignServerRelationId,
										datum,
										stmt->options,
										fdw->fdwvalidator);

		if (PointerIsValid(DatumGetPointer(datum)))
			repl_val[Anum_pg_foreign_server_srvoptions - 1] = datum;
		else
			repl_null[Anum_pg_foreign_server_srvoptions - 1] = true;

		repl_repl[Anum_pg_foreign_server_srvoptions - 1] = true;
	}

	/* Everything looks good - update the tuple */
	tp = heap_modify_tuple(tp, RelationGetDescr(rel),
						   repl_val, repl_null, repl_repl);

	CatalogTupleUpdate(rel, &tp->t_self, tp);

	InvokeObjectPostAlterHook(ForeignServerRelationId, srvId, 0);

	ObjectAddressSet(address, ForeignServerRelationId, srvId);

	heap_freetuple(tp);

	table_close(rel, RowExclusiveLock);

	return address;
}
AlterForeignServer(AlterForeignServerStmt *stmt)
{
	Relation	rel;
	HeapTuple	tp;
	Datum		repl_val[Natts_pg_foreign_server];
	bool		repl_null[Natts_pg_foreign_server];
	bool		repl_repl[Natts_pg_foreign_server];
	Oid			srvId;
	Form_pg_foreign_server srvForm;
	ObjectAddress address;

	rel = table_open(ForeignServerRelationId, RowExclusiveLock);

	tp = SearchSysCacheCopy1(FOREIGNSERVERNAME,
							 CStringGetDatum(stmt->servername));

	if (!HeapTupleIsValid(tp))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("server \"%s\" does not exist", stmt->servername)));

	srvForm = (Form_pg_foreign_server) GETSTRUCT(tp);
	srvId = srvForm->oid;

	 
	if (!pg_foreign_server_ownercheck(srvId, GetUserId()))
		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_FOREIGN_SERVER,
					   stmt->servername);

	memset(repl_val, 0, sizeof(repl_val));
	memset(repl_null, false, sizeof(repl_null));
	memset(repl_repl, false, sizeof(repl_repl));

	if (stmt->has_version)
	{
		 
		if (stmt->version)
			repl_val[Anum_pg_foreign_server_srvversion - 1] =
				CStringGetTextDatum(stmt->version);
		else
			repl_null[Anum_pg_foreign_server_srvversion - 1] = true;

		repl_repl[Anum_pg_foreign_server_srvversion - 1] = true;
	}

	if (stmt->options)
	{
		ForeignDataWrapper *fdw = GetForeignDataWrapper(srvForm->srvfdw);
		Datum		datum;
		bool		isnull;

		 
		datum = SysCacheGetAttr(FOREIGNSERVEROID,
								tp,
								Anum_pg_foreign_server_srvoptions,
								&isnull);
		if (isnull)
			datum = PointerGetDatum(NULL);

		 
		datum = transformGenericOptions(ForeignServerRelationId,
										datum,
										stmt->options,
										fdw->fdwvalidator);

		if (PointerIsValid(DatumGetPointer(datum)))
			repl_val[Anum_pg_foreign_server_srvoptions - 1] = datum;
		else
			repl_null[Anum_pg_foreign_server_srvoptions - 1] = true;

		repl_repl[Anum_pg_foreign_server_srvoptions - 1] = true;
	}

	 
	tp = heap_modify_tuple(tp, RelationGetDescr(rel),
						   repl_val, repl_null, repl_repl);

	CatalogTupleUpdate(rel, &tp->t_self, tp);

	InvokeObjectPostAlterHook(ForeignServerRelationId, srvId, 0);

	ObjectAddressSet(address, ForeignServerRelationId, srvId);

	heap_freetuple(tp);

	table_close(rel, RowExclusiveLock);

	return address;
}