8.5.4.3. Disabling mysql Auto-Reconnect
If the mysql client loses its connection
to the server while sending a query, it immediately and
automatically tries to reconnect once to the server and send
the query again. However, even if mysql
succeeds in reconnecting, your first connection has ended
and all your previous session objects and settings are lost:
temporary tables, the autocommit mode, and user-defined and
session variables. Also, any current transaction rolls back.
This behavior may be dangerous for you, as in the following
example where the server was shut down and restarted without
you knowing it:
mysql> SET @a=1;
Query OK, 0 rows affected (0.05 sec)
mysql> INSERT INTO t VALUES(@a);
ERROR 2006: MySQL server has gone away
No connection. Trying to reconnect...
Connection id: 1
Current database: test
Query OK, 1 row affected (1.30 sec)
mysql> SELECT * FROM t;
+------+
| a |
+------+
| NULL |
+------+
1 row in set (0.05 sec)
The @a user variable has been lost with
the connection, and after the reconnection it is undefined.
If it is important to have mysql
terminate with an error if the connection has been lost, you
can start the mysql client with the
--skip-reconnect option.
