Set application_name to make shardman deadlock detector happy.

Also port postgres_fdw.use_repeatable_read guc.

Author: arssher

contrib/postgres_fdw/connection.c

@@ -451,19 +451,19 @@ static void
 begin_remote_xact(ConnCacheEntry *entry)
 {
 	int			curlevel = GetCurrentTransactionNestLevel();
+	char		sql[128];
+
 
 	/* Start main transaction if we haven't yet */
 	if (entry->xact_depth <= 0)
 	{
-		const char *sql;
-
 		elog(DEBUG3, "starting remote transaction on connection %p",
 			 entry->conn);
 
-		if (IsolationIsSerializable())
-			sql = "START TRANSACTION ISOLATION LEVEL SERIALIZABLE";
-		else
-			sql = "START TRANSACTION ISOLATION LEVEL REPEATABLE READ";
+		sprintf(sql, "START TRANSACTION %s; set application_name='pgfdw:%lld:%d';",
+				IsolationIsSerializable() ? "ISOLATION LEVEL SERIALIZABLE" :
+				UseRepeatableRead ? "ISOLATION LEVEL REPEATABLE READ" : "",
+				(long long) GetSystemIdentifier(), MyProcPid);
 		entry->changing_xact_state = true;
 		do_sql_command(entry->conn, sql);
 		entry->xact_depth = 1;

contrib/postgres_fdw/postgres_fdw.c

@@ -269,6 +269,7 @@ typedef struct
 } ec_member_foreign_arg;
 
 bool		UseGlobalSnapshots;
+bool		UseRepeatableRead;
 void		_PG_init(void);
 
 /*
@@ -5805,4 +5806,8 @@ _PG_init(void)
 							 "Use global snapshots for FDW transactions", NULL,
 							 &UseGlobalSnapshots, false, PGC_USERSET, 0, NULL,
 							 NULL, NULL);
+	DefineCustomBoolVariable("postgres_fdw.use_repeatable_read",
+							 "Use repeatable read isilation error for remote transactions", NULL,
+							 &UseRepeatableRead, true, PGC_USERSET, 0, NULL,
+							 NULL, NULL);
 }

contrib/postgres_fdw/postgres_fdw.h

@@ -184,6 +184,7 @@ extern const char *get_jointype_name(JoinType jointype);
 extern bool is_builtin(Oid objectId);
 extern bool is_shippable(Oid objectId, Oid classId, PgFdwRelationInfo *fpinfo);
 
+extern bool UseRepeatableRead;
 extern bool UseGlobalSnapshots;
 
 #endif							/* POSTGRES_FDW_H */