Function GetFdwRoutineByServerId

src/backend/foreign/foreign.c:630–665

* GetFdwRoutineByServerId - look up the handler of the foreign-data wrapper * for the given foreign server, and retrieve its FdwRoutine struct. */

 * for the given foreign server, and retrieve its FdwRoutine struct.
 */
FdwRoutine *
GetFdwRoutineByServerId(Oid serverid)
{
	HeapTuple	tp;
	Form_pg_foreign_data_wrapper fdwform;
	Form_pg_foreign_server serverform;
	Oid			fdwid;
	Oid			fdwhandler;

	/* Get foreign-data wrapper OID for the server. */
	tp = SearchSysCache1(FOREIGNSERVEROID, ObjectIdGetDatum(serverid));
	if (!HeapTupleIsValid(tp))
		elog(ERROR, "cache lookup failed for foreign server %u", serverid);
	serverform = (Form_pg_foreign_server) GETSTRUCT(tp);
	fdwid = serverform->srvfdw;
	ReleaseSysCache(tp);

	/* Get handler function OID for the FDW. */
	tp = SearchSysCache1(FOREIGNDATAWRAPPEROID, ObjectIdGetDatum(fdwid));
	if (!HeapTupleIsValid(tp))
		elog(ERROR, "cache lookup failed for foreign-data wrapper %u", fdwid);
	fdwform = (Form_pg_foreign_data_wrapper) GETSTRUCT(tp);
	fdwhandler = fdwform->fdwhandler;

	/* Complain if FDW has been set to NO HANDLER. */
	if (!OidIsValid(fdwhandler))
		ereport(ERROR,
				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
				 errmsg("foreign-data wrapper \"%s\" has no handler",
						NameStr(fdwform->fdwname))));

	ReleaseSysCache(tp);

	/* And finally, call the handler function. */
	return GetFdwRoutine(fdwhandler);
}


/*