diff --git a/src/protocol/pool_process_query.c b/src/protocol/pool_process_query.c
index 202afa2a3..49bda67bc 100644
--- a/src/protocol/pool_process_query.c
+++ b/src/protocol/pool_process_query.c
@@ -1959,6 +1959,7 @@ do_query(POOL_CONNECTION *backend, char *query, POOL_SELECT_RESULT **result, int
 	int			num_close_complete;
 	int			state;
 	bool		data_pushed;
+	bool		sent_sync = false;		/* true if we sent a Sync (not Flush) */
 
 	data_pushed = false;
 
@@ -2107,21 +2108,14 @@ do_query(POOL_CONNECTION *backend, char *query, POOL_SELECT_RESULT **result, int
 		pool_write(backend, prepared_name, pname_len);
 
 		/*
-		 * Send sync or flush message. If we are in an explicit transaction,
-		 * sending "sync" is safe because it will not break unnamed portal.
-		 * Also this is desirable because if no user queries are sent after
-		 * do_query(), COMMIT command could cause statement time out, because
-		 * flush message does not clear the alarm for statement time out which
-		 * has been set when do_query() issues query.
+		 * Send Sync message. If we are in an explicit transaction, sending
+		 * "sync" is safe because it will not break user's unnamed portal.  If
+		 * we are not in an explicit transaction, sending a sync message
+		 * closes an unnamed portal.  But next user's bind message will create
+		 * the unnamed portal anyway.
 		 */
-		if (backend->tstate == 'T')
-			pool_write(backend, "S", 1);	/* send "sync" message */
-		else
-		{
-			pool_write(backend, "H", 1);	/* send "flush" message */
-			/* remember that we sent queries but did not send sync message */
-			pool_get_session_context(true)->pending_sync_map[backend->db_node_id] = true;
-		}
+		pool_write(backend, "S", 1);	/* send "sync" message */
+		sent_sync = true;
 		len = htonl(sizeof(len));
 		pool_write_and_flush(backend, &len, sizeof(len));
 	}
@@ -2232,7 +2226,7 @@ do_query(POOL_CONNECTION *backend, char *query, POOL_SELECT_RESULT **result, int
 					return;
 
 				/* If "sync" message was issued, 'Z' is expected. */
-				if (doing_extended && backend->tstate == 'T')
+				if (doing_extended && sent_sync)
 					state |= COMMAND_COMPLETE_RECEIVED;
 				break;
 
@@ -2244,7 +2238,7 @@ do_query(POOL_CONNECTION *backend, char *query, POOL_SELECT_RESULT **result, int
 				 * If "sync" message was issued, 'Z' is expected, else we are
 				 * done with 'C'.
 				 */
-				if (!doing_extended || backend->tstate != 'T')
+				if (!doing_extended || !sent_sync)
 					state |= COMMAND_COMPLETE_RECEIVED;
 
 				/*