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Excerpts from this Manual mysql_options()

int mysql_options(MYSQL *mysql, enum mysql_option option, const void *arg)


Can be used to set extra connect options and affect behavior for a connection. This function may be called multiple times to set several options.

Call mysql_options() after mysql_init() and before mysql_connect() or mysql_real_connect().

The option argument is the option that you want to set; the arg argument is the value for the option. If the option is an integer, specify a pointer to the value of the integer as the arg argument.

The following list describes the possible options, their effect, and how arg is used for each option. For option descriptions that indicate arg is unused, its value is irrelevant; it is conventional to pass 0. Several of the options apply only when the application is linked against the libmysqld embedded server library and are unused for applications linked against the libmysqlclient client library.

  • MYSQL_DEFAULT_AUTH (argument type: char *)

    The name of the authentication plugin to use.

  • MYSQL_ENABLE_CLEARTEXT_PLUGIN (argument type: my_bool *)

    Enable the mysql_clear_password cleartext authentication plugin. (See Section, “Client-Side Cleartext Pluggable Authentication”.)

  • MYSQL_INIT_COMMAND (argument type: char *)

    SQL statement to execute when connecting to the MySQL server. Automatically re-executed if reconnection occurs.

  • MYSQL_OPT_COMPRESS (argument: not used)

    Use the compressed client/server protocol.

  • MYSQL_OPT_CONNECT_TIMEOUT (argument type: unsigned int *)

    The connect timeout in seconds.

  • MYSQL_OPT_GUESS_CONNECTION (argument: not used)

    For an application linked against the libmysqld embedded server library, this enables the library to guess whether to use the embedded server or a remote server. Guess means that if the host name is set and is not localhost, it uses a remote server. This behavior is the default. MYSQL_OPT_USE_EMBEDDED_CONNECTION and MYSQL_OPT_USE_REMOTE_CONNECTION can be used to override it. This option is ignored for applications linked against the libmysqlclient client library.

  • MYSQL_OPT_LOCAL_INFILE (argument type: optional pointer to unsigned int)

    This option affects client-side LOCAL capability for LOAD DATA operations. By default, LOCAL capability is determined by the default compiled into the MySQL client library (see Section 13.2.6, “LOAD DATA INFILE Syntax”). To control this capability explicitly, invoke mysql_options() to set the MYSQL_OPT_LOCAL_INFILE option:

    • LOCAL is disabled if the pointer points to an unsigned int that has a zero value.

    • LOCAL is enabled if no pointer is given or if the pointer points to an unsigned int that has a nonzero value.

    Successful use of a LOCAL load operation by a client also requires that the server permits it.

  • MYSQL_OPT_NAMED_PIPE (argument: not used)

    Use a named pipe to connect to the MySQL server on Windows, if the server permits named-pipe connections.

  • MYSQL_OPT_PROTOCOL (argument type: unsigned int *)

    Type of protocol to use. Specify one of the enum values of mysql_protocol_type defined in mysql.h.

  • MYSQL_OPT_READ_TIMEOUT (argument type: unsigned int *)

    The timeout in seconds for each attempt to read from the server. There are retries if necessary, so the total effective timeout value is three times the option value. You can set the value so that a lost connection can be detected earlier than the TCP/IP Close_Wait_Timeout value of 10 minutes.

    Implementation of this timeout uses mechanisms that may not be available on all platforms. On such a platform, a client that issues a read call might under certain circumstances wait without timing out. For example, a client might not time out if the server is not responding because it is waiting for a disk full condition to clear.

  • MYSQL_OPT_RECONNECT (argument type: my_bool *)

    Enable or disable automatic reconnection to the server if the connection is found to have been lost. Reconnect is off by default; this option provides a way to set reconnection behavior explicitly.

  • MYSQL_OPT_SSL_MODE (argument type: unsigned int *)

    The security state to use for the connection to the server. The only permitted arument value is SSL_MODE_REQUIRED (require a secure connection). If set, this option causes mysql_real_connect() to fail if an encrypted connection cannot be obtained, without falling back to an unencrypted connection. Thus, mysql_real_connect() returns an error if the server does not support SSL or the client is not configured to use SSL. For more information about the security states, see the description of --ssl-mode in Section 6.4.5, “Command Options for Secure Connections”.

    To require an encrypted connection in MySQL 5.5, the standard MySQL client programs call mysql_options() to set MYSQL_OPT_SSL_MODE if the --ssl-mode=REQUIRED command-line option was specified. Third-party applications that must be able to require encrypted connections can use the same technique. For details, see Section, “mysql_ssl_set()”.

    This option was added in MySQL 5.5.55.

  • MYSQL_OPT_SSL_VERIFY_SERVER_CERT (argument type: my_bool *)

    Enable or disable verification of the server's Common Name value in its certificate against the host name used when connecting to the server. The connection is rejected if there is a mismatch. For encrypted connections, this feature can be used to prevent man-in-the-middle attacks. Verification is disabled by default.

  • MYSQL_OPT_USE_EMBEDDED_CONNECTION (argument: not used)

    For an application linked against the libmysqld embedded server library, this forces the use of the embedded server for the connection. This option is ignored for applications linked against the libmysqlclient client library.

  • MYSQL_OPT_USE_REMOTE_CONNECTION (argument: not used)

    For an application linked against the libmysqld embedded server library, this forces the use of a remote server for the connection. This option is ignored for applications linked against the libmysqlclient client library.

  • MYSQL_OPT_USE_RESULT (argument: not used)

    This option is unused.

  • MYSQL_OPT_WRITE_TIMEOUT (argument type: unsigned int *)

    The timeout in seconds for each attempt to write to the server. There is a retry if necessary, so the total effective timeout value is two times the option value.

  • MYSQL_PLUGIN_DIR (argument type: char *)

    The directory in which to look for client plugins.

  • MYSQL_READ_DEFAULT_FILE (argument type: char *)

    Read options from the named option file instead of from my.cnf.

  • MYSQL_READ_DEFAULT_GROUP (argument type: char *)

    Read options from the named group from my.cnf or the file specified with MYSQL_READ_DEFAULT_FILE.

  • MYSQL_REPORT_DATA_TRUNCATION (argument type: my_bool *)

    Enable or disable reporting of data truncation errors for prepared statements using the error member of MYSQL_BIND structures. (Default: enabled.)

  • MYSQL_SECURE_AUTH (argument type: my_bool *)

    Whether to connect to a server that does not support the password hashing used in MySQL 4.1.1 and later.

  • MYSQL_SET_CHARSET_DIR (argument type: char *)

    The path name to the directory that contains character set definition files.

  • MYSQL_SET_CHARSET_NAME (argument type: char *)

    The name of the character set to use as the default character set. The argument can be MYSQL_AUTODETECT_CHARSET_NAME to cause the character set to be autodetected based on the operating system setting (see Section 10.1.4, “Connection Character Sets and Collations”).

  • MYSQL_SET_CLIENT_IP (argument type: char *)

    For an application linked against the libmysqld embedded server library (when libmysqld is compiled with authentication support), this means that the user is considered to have connected from the specified IP address (specified as a string) for authentication purposes. This option is ignored for applications linked against the libmysqlclient client library.

  • MYSQL_SHARED_MEMORY_BASE_NAME (argument type: char *)

    The name of the shared-memory object for communication to the server on Windows, if the server supports shared-memory connections. Specify the same value as the --shared-memory-base-name option used for the mysqld server you want to connect to.

The client group is always read if you use MYSQL_READ_DEFAULT_FILE or MYSQL_READ_DEFAULT_GROUP.

The specified group in the option file may contain the following options.

character-sets-dir=dir_nameThe directory where character sets are installed.
compressUse the compressed client/server protocol.
connect-timeout=secondsThe connect timeout in seconds. On Linux this timeout is also used for waiting for the first answer from the server.
database=db_nameConnect to this database if no database was specified in the connect command.
debugDebug options.
default-character-set=charset_nameThe default character set to use.
disable-local-infileDisable use of LOAD DATA LOCAL INFILE.
enable-cleartext-pluginEnable the mysql_clear_password cleartext authentication plugin. Added in MySQL 5.5.27.
host=host_nameDefault host name.
init-command=stmtStatement to execute when connecting to MySQL server. Automatically re-executed if reconnection occurs.
interactive-timeout=secondsSame as specifying CLIENT_INTERACTIVE to mysql_real_connect(). See Section, “mysql_real_connect()”.
local-infile[={0|1}]If no argument or nonzero argument, enable use of LOAD DATA LOCAL; otherwise disable.
max_allowed_packet=bytesMaximum size of packet that client can read from server.
multi-queries, multi-resultsEnable multiple result sets from multiple-statement executions or stored procedures.
multi-statementsEnable the client to send multiple statements in a single string (separated by ; characters).
password=passwordDefault password.
pipeUse named pipes to connect to a MySQL server on Windows.
port=port_numDefault port number.
protocol={TCP|SOCKET|PIPE|MEMORY}The protocol to use when connecting to the server.
return-found-rowsTell mysql_info() to return found rows instead of updated rows when using UPDATE.
shared-memory-base-name=nameShared-memory name to use to connect to server.
socket={file_name|pipe_name}Default socket file.
ssl-ca=file_nameCertificate Authority file.
ssl-capath=dir_nameCertificate Authority directory.
ssl-cert=file_nameCertificate file.
ssl-cipher=cipher_listPermissible SSL ciphers.
ssl-key=file_nameKey file.
timeout=secondsLike connect-timeout.
userDefault user.

timeout has been replaced by connect-timeout, but timeout is still supported for backward compatibility.

For more information about option files used by MySQL programs, see Section 4.2.6, “Using Option Files”.

Return Values

Zero for success. Nonzero if you specify an unknown option.


The following mysql_options() calls request the use of compression in the client/server protocol, cause options to be read from the [odbc] group of option files, and disable transaction autocommit mode:

MYSQL mysql;

mysql_options(&mysql,MYSQL_INIT_COMMAND,"SET autocommit=0");
if (!mysql_real_connect(&mysql,"host","user","passwd","database",0,NULL,0))
    fprintf(stderr, "Failed to connect to database: Error: %s\n",

This code requests that the client use the compressed client/server protocol and read the additional options from the odbc section in the my.cnf file.

User Comments
  Posted by Rupert Peddle on December 15, 2008
When retrying a connection, I used mysql_options() to set a connection timeout then called mysql_real_connect in a while loop:



Doing this, it appears that the connection timeout was lost after the first iteration. I had to re-set the connection timeout after every attempt:



Don't know if this is the case for other options....
  Posted by Uros Reljic on April 23, 2009
Set flag CLIENT_REMEMBER_OPTIONS in client_flag when you calling mysql_real_connect().
Without this flag, if mysql_real_connect() fails, you must repeat the mysql_options() calls before trying to connect again.

  Posted by Gary Wallis on April 15, 2010
Here is some example code that can provide usec timeout for mysql_real_connect(), is based on a non blocking test connection before doing the actual mysql_real_connect().

You can find the complete example here:

printf("Could not create socket\n");
// Set non-blocking

//Fallback to DBIP1
iConRes=connect(iSock,(struct sockaddr *)&sockaddr_inMySQLServer,sizeof(sockaddr_inMySQLServer));
printf("Error in connection() %d - %s\n",valopt,strerror(valopt));
//Valid fast connection
close(iSock);//Don't need anymore.
printf("Connected to %s:%s\n",(char *)DBIP1,cPort);
printf("DBIP1 else if select()\n");
printf("DBIP1 else if errno==EINPROGRESS\n");
close(iSock);//Don't need anymore.

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