mysql> show variables like '%timeout';
+-----------------------------------+----------+
| Variable_name                     | Value    |
+-----------------------------------+----------+
| connect_timeout                   | 10       |
| delayed_insert_timeout            | 300      |
| have_statement_timeout            | YES      |
| innodb_flush_log_at_timeout       | 1        |
| innodb_lock_wait_timeout          | 50       |
| innodb_rollback_on_timeout        | OFF      |
| interactive_timeout               | 28800    |
| lock_wait_timeout                 | 31536000 |
| mysqlx_connect_timeout            | 30       |
| mysqlx_idle_worker_thread_timeout | 60       |
| mysqlx_interactive_timeout        | 28800    |
| mysqlx_port_open_timeout          | 0        |
| mysqlx_read_timeout               | 30       |
| mysqlx_wait_timeout               | 28800    |
| mysqlx_write_timeout              | 60       |
| net_read_timeout                  | 30       |
| net_write_timeout                 | 60       |
| rpl_stop_slave_timeout            | 31536000 |
| slave_net_timeout                 | 60       |
| wait_timeout                      | 28800    |
+-----------------------------------+----------+
20 rows in set, 1 warning (0.00 sec)

enum mysql_option {
  MYSQL_OPT_CONNECT_TIMEOUT,
  MYSQL_OPT_COMPRESS,
  MYSQL_OPT_NAMED_PIPE,
  MYSQL_INIT_COMMAND,
  MYSQL_READ_DEFAULT_FILE,
  MYSQL_READ_DEFAULT_GROUP,
  MYSQL_SET_CHARSET_DIR,
  MYSQL_SET_CHARSET_NAME,
  MYSQL_OPT_LOCAL_INFILE,
  MYSQL_OPT_PROTOCOL,
  MYSQL_SHARED_MEMORY_BASE_NAME,
  MYSQL_OPT_READ_TIMEOUT,
  MYSQL_OPT_WRITE_TIMEOUT,
  MYSQL_OPT_USE_RESULT,
  MYSQL_REPORT_DATA_TRUNCATION,
  MYSQL_OPT_RECONNECT,
  MYSQL_PLUGIN_DIR,
  MYSQL_DEFAULT_AUTH,
  MYSQL_OPT_BIND,
  MYSQL_OPT_SSL_KEY,
  MYSQL_OPT_SSL_CERT,
  MYSQL_OPT_SSL_CA,
  MYSQL_OPT_SSL_CAPATH,
  MYSQL_OPT_SSL_CIPHER,
  MYSQL_OPT_SSL_CRL,
  MYSQL_OPT_SSL_CRLPATH,
  MYSQL_OPT_CONNECT_ATTR_RESET,
  MYSQL_OPT_CONNECT_ATTR_ADD,
  MYSQL_OPT_CONNECT_ATTR_DELETE,
  MYSQL_SERVER_PUBLIC_KEY,
  MYSQL_ENABLE_CLEARTEXT_PLUGIN,
  MYSQL_OPT_CAN_HANDLE_EXPIRED_PASSWORDS,
  MYSQL_OPT_MAX_ALLOWED_PACKET,
  MYSQL_OPT_NET_BUFFER_LENGTH,
  MYSQL_OPT_TLS_VERSION,
  MYSQL_OPT_SSL_MODE,
  MYSQL_OPT_GET_SERVER_PUBLIC_KEY,
  MYSQL_OPT_RETRY_COUNT,
  MYSQL_OPT_OPTIONAL_RESULTSET_METADATA,
  MYSQL_OPT_SSL_FIPS_MODE,
  MYSQL_OPT_TLS_CIPHERSUITES,
  MYSQL_OPT_COMPRESSION_ALGORITHMS,
  MYSQL_OPT_ZSTD_COMPRESSION_LEVEL
};

 

wait_timeout

Property	Value
Command-Line Format	--wait-timeout=#
System Variable	wait_timeout
Scope	Global, Session
Dynamic	Yes
SET_VAR Hint Applies	No
Type	Integer
Default Value	28800
Minimum Value	1
Maximum Value (Other)	31536000
Maximum Value (Windows)	2147483

The number of seconds the server waits for activity on a noninteractive connection before closing it.

On thread startup, the session wait_timeout value is initialized from the global wait_timeout value or from the global interactive_timeout value, depending on the type of client (as defined by the CLIENT_INTERACTIVE connect option to mysql_real_connect()). See also interactive_timeout.

 

28.7.27 C API Automatic Reconnection Control

The MySQL client library can perform an automatic reconnection to the server if it finds that the connection is down when you attempt to send a statement to the server to be executed. If auto-reconnect is enabled, the library tries once to reconnect to the server and send the statement again.

Auto-reconnect is disabled by default.

If it is important for your application to know that the connection has been dropped (so that it can exit or take action to adjust for the loss of state information), be sure that auto-reconnect is disabled. To ensure this, call mysql_options() with the MYSQL_OPT_RECONNECT option:

bool reconnect = 0;
mysql_options(&mysql, MYSQL_OPT_RECONNECT, &reconnect);

If the connection has gone down, the effect of mysql_ping() depends on the auto-reconnect state. If auto-reconnect is enabled, mysql_ping() performs a reconnect. Otherwise, it returns an error.

Some client programs might provide the capability of controlling automatic reconnection. For example, mysql reconnects by default, but the --skip-reconnect option can be used to suppress this behavior.

If an automatic reconnection does occur (for example, as a result of calling mysql_ping()), there is no explicit indication of it. To check for reconnection, callmysql_thread_id() to get the original connection identifier before calling mysql_ping(), then call mysql_thread_id() again to see whether the identifier changed.

Automatic reconnection can be convenient because you need not implement your own reconnect code, but if a reconnection does occur, several aspects of the connection state are reset on the server side and your application will not be notified.

The connection-related state is affected as follows:

• Any active transactions are rolled back and autocommit mode is reset.

• All table locks are released.

• All TEMPORARY tables are closed (and dropped).

• Session system variables are reinitialized to the values of the corresponding global system variables, including system variables that are set implicitly by statements such as SET NAMES.

• User variable settings are lost.

• Prepared statements are released.

• HANDLER variables are closed.

• The value of LAST_INSERT_ID() is reset to 0.

• Locks acquired with GET_LOCK() are released.

• The association of the client with the Performance Schema threads table row that determines connection thread instrumentation is lost. If the client reconnects after a disconnect, the session is associated with a new row in the threads table and the thread monitoring state may be different. See Section 26.12.19.5, “The threads Table”.

If reconnection occurs, any SQL statement specified by calling mysql_options() with the MYSQL_INIT_COMMAND option is re-executed.

If the connection drops, it is possible that the session associated with the connection on the server side will still be running if the server has not yet detected that the client is no longer connected. In this case, any locks held by the original connection still belong to that session, so you may want to kill it by calling mysql_kill().

 

void QSqlDatabase::setConnectOptions(const QString &options = QString())

Sets database-specific options. This must be done before the connection is opened or it has no effect (or you can close() the connection, call this function and open() the connection again).

The format of the options string is a semicolon separated list of option names or option=value pairs. The options depend on the database client used:

 

ODBC	MySQL	PostgreSQL
SQL_ATTR_ACCESS_MODE SQL_ATTR_LOGIN_TIMEOUT SQL_ATTR_CONNECTION_TIMEOUT SQL_ATTR_CURRENT_CATALOG SQL_ATTR_METADATA_ID SQL_ATTR_PACKET_SIZE SQL_ATTR_TRACEFILE SQL_ATTR_TRACE SQL_ATTR_CONNECTION_POOLING SQL_ATTR_ODBC_VERSION	CLIENT_COMPRESS CLIENT_FOUND_ROWS CLIENT_IGNORE_SPACE CLIENT_ODBC CLIENT_NO_SCHEMA CLIENT_INTERACTIVE UNIX_SOCKET MYSQL_OPT_RECONNECT MYSQL_OPT_CONNECT_TIMEOUT MYSQL_OPT_READ_TIMEOUT MYSQL_OPT_WRITE_TIMEOUT SSL_KEY SSL_CERT SSL_CA SSL_CAPATH SSL_CIPHER	connect_timeout options tty requiressl service
DB2	OCI	TDS
SQL_ATTR_ACCESS_MODE SQL_ATTR_LOGIN_TIMEOUT	OCI_ATTR_PREFETCH_ROWS OCI_ATTR_PREFETCH_MEMORY	none
SQLite	Interbase
QSQLITE_BUSY_TIMEOUT QSQLITE_OPEN_READONLY QSQLITE_OPEN_URI QSQLITE_ENABLE_SHARED_CACHE	ISC_DPB_LC_CTYPE ISC_DPB_SQL_ROLE_NAME

Examples:

  ...

  // MySQL connection

  db.setConnectOptions("SSL_KEY=client-key.pem;SSL_CERT=client-cert.pem;SSL_CA=ca-cert.pem;CLIENT_IGNORE_SPACE=1"); // use an SSL connection to the server

  if (!db.open()) {

      db.setConnectOptions(); // clears the connect option string

      ...

  }

  ...

  // PostgreSQL connection

  db.setConnectOptions("requiressl=1"); // enable PostgreSQL SSL connections

  if (!db.open()) {

      db.setConnectOptions(); // clear options

      ...

  }

  ...

  // ODBC connection

  db.setConnectOptions("SQL_ATTR_ACCESS_MODE=SQL_MODE_READ_ONLY;SQL_ATTR_TRACE=SQL_OPT_TRACE_ON"); // set ODBC options

  if (!db.open()) {

      db.setConnectOptions(); // don't try to set this option

      ...

  }

Refer to the client library documentation for more information about the different options.

See also connectOptions().