Options that affect security: See Section 6.1.4, “Security-Related mysqld Options and Variables”.

SSL-related options: See Command Options for Encrypted Connections.

Binary log control options: See Section 5.4.4, “The Binary Log”.

Replication-related options: See Section 16.1.6, “Replication and Binary Logging Options and Variables”.

Options for loading plugins such as pluggable storage engines: See Section 5.5.1, “Installing and Uninstalling Plugins”.

Options specific to particular storage engines: See Section 14.15, “InnoDB Startup Options and System Variables” and Section 15.2.1, “MyISAM Startup Options”.

--help, -?

Display a short help message and exit. Use both the --verbose and --help options to see the full message.

--allow-suspicious-udfs

This option controls whether loadable functions that have only an xxx symbol for the main function can be loaded. By default, the option is off and only loadable functions that have at least one auxiliary symbol can be loaded; this prevents attempts at loading functions from shared object files other than those containing legitimate functions. See Loadable Function Security Precautions.

--ansi

Use standard (ANSI) SQL syntax instead of MySQL syntax. For more precise control over the server SQL mode, use the --sql-mode option instead. See Section 1.6, “MySQL Standards Compliance”, and Section 5.1.10, “Server SQL Modes”.

--basedir=dir_name, -b dir_name

The path to the MySQL installation directory. This option sets the basedir system variable.

--bootstrap

This option is used by the mysql_install_db program to create the MySQL privilege tables without having to start a full MySQL server.

--bootstrap is mutually exclusive with --daemonize, --initialize, and --initialize-insecure.

Global transaction identifiers (GTIDs) are not disabled when --bootstrap is used. --bootstrap was used (Bug #20980271). See Section 16.1.3, “Replication with Global Transaction Identifiers”.

When the server operates in bootstap mode, some functionality is unavailable that limits the statements permitted in any file named by the init_file system variable. For more information, see the description of that variable. In addition, the disabled_storage_engines system variable has no effect.

--character-set-client-handshake

Do not ignore character set information sent by the client. To ignore client information and use the default server character set, use --skip-character-set-client-handshake; this makes MySQL behave like MySQL 4.0.

--chroot=dir_name, -r dir_name

Put the mysqld server in a closed environment during startup by using the chroot() system call. This is a recommended security measure. Use of this option somewhat limits LOAD DATA and SELECT ... INTO OUTFILE.

--console

(Windows only.) Write the error log to stderr and stdout (the console). mysqld does not close the console window if this option is used.

--console takes precedence over --log-error if both are given. (In MySQL 5.5 and 5.6, this is reversed: --log-error takes precedence over --console if both are given.)

--core-file

When this option is used, write a core file if mysqld dies; no arguments are needed (or accepted). The name and location of the core file is system dependent. On Linux, a core file named core.pid is written to the current working directory of the process, which for mysqld is the data directory. pid represents the process ID of the server process. On macOS, a core file named core.pid is written to the /cores directory. On Solaris, use the coreadm command to specify where to write the core file and how to name it.

For some systems, to get a core file you must also specify the --core-file-size option to mysqld_safe. See Section 4.3.2, “mysqld_safe — MySQL Server Startup Script”. On some systems, such as Solaris, you do not get a core file if you are also using the --user option. There might be additional restrictions or limitations. For example, it might be necessary to execute ulimit -c unlimited before starting the server. Consult your system documentation.

--daemonize

This option causes the server to run as a traditional, forking daemon, permitting it to work with operating systems that use systemd for process control. For more information, see Section 2.5.10, “Managing MySQL Server with systemd”.

--daemonize is mutually exclusive with --bootstrap, --initialize, and --initialize-insecure.

--datadir=dir_name, -h dir_name

The path to the MySQL server data directory. This option sets the datadir system variable. See the description of that variable.

--debug[=debug_options], -# [debug_options]

If MySQL is configured with the -DWITH_DEBUG=1 CMake option, you can use this option to get a trace file of what mysqld is doing. A typical debug_options string is d:t:o,file_name. The default is d:t:i:o,/tmp/mysqld.trace on Unix and d:t:i:O,\mysqld.trace on Windows.

Using -DWITH_DEBUG=1 to configure MySQL with debugging support enables you to use the --debug="d,parser_debug" option when you start the server. This causes the Bison parser that is used to process SQL statements to dump a parser trace to the server's standard error output. Typically, this output is written to the error log.

This option may be given multiple times. Values that begin with + or - are added to or subtracted from the previous value. For example, --debug=T --debug=+P sets the value to P:T.

For more information, see Section 5.8.3, “The DBUG Package”.

--debug-sync-timeout[=N]

Controls whether the Debug Sync facility for testing and debugging is enabled. Use of Debug Sync requires that MySQL be configured with the -DWITH_DEBUG=ON CMake option (see Section 2.8.7, “MySQL Source-Configuration Options”). If Debug Sync is not compiled in, this option is not available. The option value is a timeout in seconds. The default value is 0, which disables Debug Sync. To enable it, specify a value greater than 0; this value also becomes the default timeout for individual synchronization points. If the option is given without a value, the timeout is set to 300 seconds.

For a description of the Debug Sync facility and how to use synchronization points, see MySQL Internals: Test Synchronization.

--default-time-zone=timezone

Set the default server time zone. This option sets the global time_zone system variable. If this option is not given, the default time zone is the same as the system time zone (given by the value of the system_time_zone system variable.

The system_time_zone variable differs from time_zone. Although they might have the same value, the latter variable is used to initialize the time zone for each client that connects. See Section 5.1.13, “MySQL Server Time Zone Support”.

--defaults-extra-file=file_name

Read this option file after the global option file but (on Unix) before the user option file. If the file does not exist or is otherwise inaccessible, an error occurs. If file_name is not an absolute path name, it is interpreted relative to the current directory. This must be the first option on the command line if it is used.

For additional information about this and other option-file options, see Section 4.2.2.3, “Command-Line Options that Affect Option-File Handling”.

--defaults-file=file_name

Read only the given option file. If the file does not exist or is otherwise inaccessible, an error occurs. If file_name is not an absolute path name, it is interpreted relative to the current directory.

For additional information about this and other option-file options, see Section 4.2.2.3, “Command-Line Options that Affect Option-File Handling”.

--defaults-group-suffix=str

Read not only the usual option groups, but also groups with the usual names and a suffix of str. For example, mysqld normally reads the [mysqld] group. If this option is given as --defaults-group-suffix=_other, mysqld also reads the [mysqld_other] group.

For additional information about this and other option-file options, see Section 4.2.2.3, “Command-Line Options that Affect Option-File Handling”.

--des-key-file=file_name

Read the default DES keys from this file. These keys are used by the DES_ENCRYPT() and DES_DECRYPT() functions.

--disable-partition-engine-check

Whether to disable the startup check for tables with nonnative partitioning.

As of MySQL 5.7.17, the generic partitioning handler in the MySQL server is deprecated, and is removed in MySQL 8.0, when the storage engine used for a given table is expected to provide its own (“native”) partitioning handler. Currently, only the InnoDB and NDB storage engines do this.

Use of tables with nonnative partitioning results in an ER_WARN_DEPRECATED_SYNTAX warning. In MySQL 5.7.17 through 5.7.20, the server automatically performs a check at startup to identify tables that use nonnative partitioning; for any that are found, the server writes a message to its error log. To disable this check, use the --disable-partition-engine-check option. In MySQL 5.7.21 and later, this check is not performed; in these versions, you must start the server with --disable-partition-engine-check=false, if you wish for the server to check for tables using the generic partitioning handler (Bug #85830, Bug #25846957).

Use of tables with nonnative partitioning results in an ER_WARN_DEPRECATED_SYNTAX warning. Also, the server performs a check at startup to identify tables that use nonnative partitioning; for any found, the server writes a message to its error log. To disable this check, use the --disable-partition-engine-check option.

To prepare for migration to MySQL 8.0, any table with nonnative partitioning should be changed to use an engine that provides native partitioning, or be made nonpartitioned. For example, to change a table to InnoDB, execute this statement:

ALTER TABLE table_name ENGINE = INNODB;

--early-plugin-load=plugin_list

This option tells the server which plugins to load before loading mandatory built-in plugins and before storage engine initialization. Early loading is supported only for plugins compiled with PLUGIN_OPT_ALLOW_EARLY. If multiple --early-plugin-load options are given, only the last one applies.

The option value is a semicolon-separated list of plugin_library and name=plugin_library values. Each plugin_library is the name of a library file that contains plugin code, and each name is the name of a plugin to load. If a plugin library is named without any preceding plugin name, the server loads all plugins in the library. With a preceding plugin name, the server loads only the named plugin from the libary. The server looks for plugin library files in the directory named by the plugin_dir system variable.

For example, if plugins named myplug1 and myplug2 are contained in the plugin library files myplug1.so and myplug2.so, use this option to perform an early plugin load:

mysqld --early-plugin-load="myplug1=myplug1.so;myplug2=myplug2.so"

Quotes surround the argument value because otherwise some command interpreters interpret semicolon (;) as a special character. (For example, Unix shells treat it as a command terminator.)

Each named plugin is loaded early for a single invocation of mysqld only. After a restart, the plugin is not loaded early unless --early-plugin-load is used again.

If the server is started using --initialize or --initialize-insecure, plugins specified by --early-plugin-load are not loaded.

If the server is run with --help, plugins specified by --early-plugin-load are loaded but not initialized. This behavior ensures that plugin options are displayed in the help message.

InnoDB tablespace encryption relies on the MySQL Keyring for encryption key management, and the keyring plugin to be used must be loaded prior to storage engine initialization to facilitate InnoDB recovery for encrypted tables. For example, administrators who want the keyring_file plugin loaded at startup should use --early-plugin-load with the appropriate option value (such as keyring_file.so on Unix and Unix-like systems or keyring_file.dll on Windows).

For information about InnoDB tablespace encryption, see Section 14.14, “InnoDB Data-at-Rest Encryption”. For general information about plugin loading, see Section 5.5.1, “Installing and Uninstalling Plugins”.

--exit-info[=flags], -T [flags]

This is a bitmask of different flags that you can use for debugging the mysqld server. Do not use this option unless you know exactly what it does!

--external-locking

Enable external locking (system locking), which is disabled by default. If you use this option on a system on which lockd does not fully work (such as Linux), it is easy for mysqld to deadlock.

To disable external locking explicitly, use --skip-external-locking.

External locking affects only MyISAM table access. For more information, including conditions under which it can and cannot be used, see Section 8.11.5, “External Locking”.

--flush

Flush (synchronize) all changes to disk after each SQL statement. Normally, MySQL does a write of all changes to disk only after each SQL statement and lets the operating system handle the synchronizing to disk. See Section B.3.3.3, “What to Do If MySQL Keeps Crashing”.

--gdb

Install an interrupt handler for SIGINT (needed to stop mysqld with ^C to set breakpoints) and disable stack tracing and core file handling. See Section 5.8.1.4, “Debugging mysqld under gdb”.

--ignore-db-dir=dir_name

This option tells the server to ignore the given directory name for purposes of the SHOW DATABASES statement or INFORMATION_SCHEMA tables. For example, if a MySQL configuration locates the data directory at the root of a file system on Unix, the system might create a lost+found directory there that the server should ignore. Starting the server with --ignore-db-dir=lost+found causes that name not to be listed as a database.

To specify more than one name, use this option multiple times, once for each name. Specifying the option with an empty value (that is, as --ignore-db-dir=) resets the directory list to the empty list.

Instances of this option given at server startup are used to set the ignore_db_dirs system variable.

This option is deprecated in MySQL 5.7. With the introduction of the data dictionary in MySQL 8.0, it became superfluous and was removed in that version.

--initialize

This option is used to initialize a MySQL installation by creating the data directory and populating the tables in the mysql system database. For more information, see Section 2.9.1, “Initializing the Data Directory”.

This option limits the effects of, or is not compatible with, a number of other startup options for the MySQL server. Some of the most common issues of this sort are noted here:

The items in the preceding list also apply when initializing the server using the --initialize-insecure option.

--initialize-insecure

This option is used to initialize a MySQL installation by creating the data directory and populating the tables in the mysql system database. This option implies --initialize, and the same restrictions and limitations apply; for more information, see the description of that option, and Section 2.9.1, “Initializing the Data Directory”.

--innodb-xxx

Set an option for the InnoDB storage engine. The InnoDB options are listed in Section 14.15, “InnoDB Startup Options and System Variables”.

--install [service_name]

(Windows only) Install the server as a Windows service that starts automatically during Windows startup. The default service name is MySQL if no service_name value is given. For more information, see Section 2.3.4.8, “Starting MySQL as a Windows Service”.

--install-manual [service_name]

(Windows only) Install the server as a Windows service that must be started manually. It does not start automatically during Windows startup. The default service name is MySQL if no service_name value is given. For more information, see Section 2.3.4.8, “Starting MySQL as a Windows Service”.

--language=lang_name, -L lang_name

The language to use for error messages. lang_name can be given as the language name or as the full path name to the directory where the language files are installed. See Section 10.12, “Setting the Error Message Language”.

--lc-messages-dir and --lc-messages should be used rather than --language, which is deprecated (and handled as a synonym for --lc-messages-dir). You should expect the --language option to be removed in a future release of MySQL.

--large-pages

Some hardware/operating system architectures support memory pages greater than the default (usually 4KB). The actual implementation of this support depends on the underlying hardware and operating system. Applications that perform a lot of memory accesses may obtain performance improvements by using large pages due to reduced Translation Lookaside Buffer (TLB) misses.

MySQL supports the Linux implementation of large page support (which is called HugeTLB in Linux). See Section 8.12.4.3, “Enabling Large Page Support”. For Solaris support of large pages, see the description of the --super-large-pages option.

--large-pages is disabled by default.

--lc-messages=locale_name

The locale to use for error messages. The default is en_US. The server converts the argument to a language name and combines it with the value of --lc-messages-dir to produce the location for the error message file. See Section 10.12, “Setting the Error Message Language”.

--lc-messages-dir=dir_name

The directory where error messages are located. The server uses the value together with the value of --lc-messages to produce the location for the error message file. See Section 10.12, “Setting the Error Message Language”.

--local-service

(Windows only) A --local-service option following the service name causes the server to run using the LocalService Windows account that has limited system privileges. If both --defaults-file and --local-service are given following the service name, they can be in any order. See Section 2.3.4.8, “Starting MySQL as a Windows Service”.

--log-error[=file_name]

Write the error log and startup messages to this file. See Section 5.4.2, “The Error Log”.

If the option names no file, the error log file name on Unix and Unix-like systems is host_name.err in the data directory. The file name on Windows is the same, unless the --pid-file option is specified. In that case, the file name is the PID file base name with a suffix of .err in the data directory.

If the option names a file, the error log file has that name (with an .err suffix added if the name has no suffix), located under the data directory unless an absolute path name is given to specify a different location.

On Windows, --console takes precedence over --log-error if both are given. In this case, the server writes the error log to the console rather than to a file. (In MySQL 5.5 and 5.6, this is reversed: --log-error takes precedence over --console if both are given.)

--log-isam[=file_name]

Log all MyISAM changes to this file (used only when debugging MyISAM).

--log-raw

Passwords in certain statements written to the general query log, slow query log, and binary log are rewritten by the server not to occur literally in plain text. Password rewriting can be suppressed for the general query log by starting the server with the --log-raw option. This option may be useful for diagnostic purposes, to see the exact text of statements as received by the server, but for security reasons is not recommended for production use.

If a query rewrite plugin is installed, the --log-raw option affects statement logging as follows:

For more information, see Section 6.1.2.3, “Passwords and Logging”.

--log-short-format

Log less information to the slow query log, if it has been activated.

--log-tc=file_name

The name of the memory-mapped transaction coordinator log file (for XA transactions that affect multiple storage engines when the binary log is disabled). The default name is tc.log. The file is created under the data directory if not given as a full path name. This option is unused.

--log-tc-size=size

The size in bytes of the memory-mapped transaction coordinator log. The default and minimum values are 6 times the page size, and the value must be a multiple of the page size. (Before MySQL 5.7.21, the default size is 24KB.)

--log-warnings[=level], -W [level]

Whether to produce additional warning messages to the error log. This option is enabled by default. To disable it, use --log-warnings=0. Specifying the option without a level value increments the current value by 1. The server logs messages about statements that are unsafe for statement-based logging if the value is greater than 0. Aborted connections and access-denied errors for new connection attempts are logged if the value is greater than 1. See Section B.3.2.9, “Communication Errors and Aborted Connections”.

--memlock

Lock the mysqld process in memory. This option might help if you have a problem where the operating system is causing mysqld to swap to disk.

--memlock works on systems that support the mlockall() system call; this includes Solaris, most Linux distributions that use a 2.4 or higher kernel, and perhaps other Unix systems. On Linux systems, you can tell whether or not mlockall() (and thus this option) is supported by checking to see whether or not it is defined in the system mman.h file, like this:

$> grep mlockall /usr/include/sys/mman.h

If mlockall() is supported, you should see in the output of the previous command something like the following:

extern int mlockall (int __flags) __THROW;

--myisam-block-size=N

The block size to be used for MyISAM index pages.

--no-defaults

Do not read any option files. If program startup fails due to reading unknown options from an option file, --no-defaults can be used to prevent them from being read. This must be the first option on the command line if it is used.

For additional information about this and other option-file options, see Section 4.2.2.3, “Command-Line Options that Affect Option-File Handling”.

--old-style-user-limits

Enable old-style user limits. (Before MySQL 5.0.3, account resource limits were counted separately for each host from which a user connected rather than per account row in the user table.) See Section 6.2.16, “Setting Account Resource Limits”.

--partition[=value]

Enables or disables user-defined partitioning support in the MySQL Server.

This option is deprecated in MySQL 5.7.16, and is removed from MySQL 8.0 because in MySQL 8.0, the partitioning engine is replaced by native partitioning, which cannot be disabled.

--performance-schema-xxx

Configure a Performance Schema option. For details, see Section 25.14, “Performance Schema Command Options”.

--plugin-load=plugin_list

This option tells the server to load the named plugins at startup. If multiple --plugin-load options are given, only the last one applies. Additional plugins to load may be specified using --plugin-load-add options.

The option value is a semicolon-separated list of plugin_library and name=plugin_library values. Each plugin_library is the name of a library file that contains plugin code, and each name is the name of a plugin to load. If a plugin library is named without any preceding plugin name, the server loads all plugins in the library. With a preceding plugin name, the server loads only the named plugin from the libary. The server looks for plugin library files in the directory named by the plugin_dir system variable.

For example, if plugins named myplug1 and myplug2 are contained in the plugin library files myplug1.so and myplug2.so, use this option to perform an early plugin load:

mysqld --plugin-load="myplug1=myplug1.so;myplug2=myplug2.so"

Quotes surround the argument value because otherwise some command interpreters interpret semicolon (;) as a special character. (For example, Unix shells treat it as a command terminator.)

Each named plugin is loaded for a single invocation of mysqld only. After a restart, the plugin is not loaded unless --plugin-load is used again. This is in contrast to INSTALL PLUGIN, which adds an entry to the mysql.plugins table to cause the plugin to be loaded for every normal server startup.

During the normal startup sequence, the server determines which plugins to load by reading the mysql.plugins system table. If the server is started with the --skip-grant-tables option, plugins registered in the mysql.plugins table are not loaded and are unavailable. --plugin-load enables plugins to be loaded even when --skip-grant-tables is given. --plugin-load also enables plugins to be loaded at startup that cannot be loaded at runtime.

This option does not set a corresponding system variable. The output of SHOW PLUGINS provides information about loaded plugins. More detailed information can be found in the Information Schema PLUGINS table. See Section 5.5.2, “Obtaining Server Plugin Information”.

For additional information about plugin loading, see Section 5.5.1, “Installing and Uninstalling Plugins”.

--plugin-load-add=plugin_list

This option complements the --plugin-load option. --plugin-load-add adds a plugin or plugins to the set of plugins to be loaded at startup. The argument format is the same as for --plugin-load. --plugin-load-add can be used to avoid specifying a large set of plugins as a single long unwieldy --plugin-load argument.

--plugin-load-add can be given in the absence of --plugin-load, but any instance of --plugin-load-add that appears before --plugin-load has no effect because --plugin-load resets the set of plugins to load. In other words, these options:

--plugin-load=x --plugin-load-add=y

are equivalent to this option:

--plugin-load="x;y"

But these options:

--plugin-load-add=y --plugin-load=x

are equivalent to this option:

--plugin-load=x

This option does not set a corresponding system variable. The output of SHOW PLUGINS provides information about loaded plugins. More detailed information can be found in the Information Schema PLUGINS table. See Section 5.5.2, “Obtaining Server Plugin Information”.

For additional information about plugin loading, see Section 5.5.1, “Installing and Uninstalling Plugins”.

--plugin-xxx

Specifies an option that pertains to a server plugin. For example, many storage engines can be built as plugins, and for such engines, options for them can be specified with a --plugin prefix. Thus, the --innodb-file-per-table option for InnoDB can be specified as --plugin-innodb-file-per-table.

For boolean options that can be enabled or disabled, the --skip prefix and other alternative formats are supported as well (see Section 4.2.2.4, “Program Option Modifiers”). For example, --skip-plugin-innodb-file-per-table disables innodb-file-per-table.

The rationale for the --plugin prefix is that it enables plugin options to be specified unambiguously if there is a name conflict with a built-in server option. For example, were a plugin writer to name a plugin “sql” and implement a “mode” option, the option name might be --sql-mode, which would conflict with the built-in option of the same name. In such cases, references to the conflicting name are resolved in favor of the built-in option. To avoid the ambiguity, users can specify the plugin option as --plugin-sql-mode. Use of the --plugin prefix for plugin options is recommended to avoid any question of ambiguity.

--port=port_num, -P port_num

The port number to use when listening for TCP/IP connections. On Unix and Unix-like systems, the port number must be 1024 or higher unless the server is started by the root operating system user. Setting this option to 0 causes the default value to be used.

--port-open-timeout=num

On some systems, when the server is stopped, the TCP/IP port might not become available immediately. If the server is restarted quickly afterward, its attempt to reopen the port can fail. This option indicates how many seconds the server should wait for the TCP/IP port to become free if it cannot be opened. The default is not to wait.

--print-defaults

Print the program name and all options that it gets from option files. Password values are masked. This must be the first option on the command line if it is used, except that it may be used immediately after --defaults-file or --defaults-extra-file.

For additional information about this and other option-file options, see Section 4.2.2.3, “Command-Line Options that Affect Option-File Handling”.

--remove [service_name]

(Windows only) Remove a MySQL Windows service. The default service name is MySQL if no service_name value is given. For more information, see Section 2.3.4.8, “Starting MySQL as a Windows Service”.

--safe-user-create

If this option is enabled, a user cannot create new MySQL users by using the GRANT statement unless the user has the INSERT privilege for the mysql.user system table or any column in the table. If you want a user to have the ability to create new users that have those privileges that the user has the right to grant, you should grant the user the following privilege:

GRANT INSERT(user) ON mysql.user TO 'user_name'@'host_name';

This ensures that the user cannot change any privilege columns directly, but has to use the GRANT statement to give privileges to other users.

--skip-grant-tables

This option affects the server startup sequence:

--skip-host-cache

Disable use of the internal host cache for faster name-to-IP resolution. With the cache disabled, the server performs a DNS lookup every time a client connects.

Use of --skip-host-cache is similar to setting the host_cache_size system variable to 0, but host_cache_size is more flexible because it can also be used to resize, enable, or disable the host cache at runtime, not just at server startup.

Starting the server with --skip-host-cache does not prevent runtime changes to the value of host_cache_size, but such changes have no effect and the cache is not re-enabled even if host_cache_size is set larger than 0.

For more information about how the host cache works, see Section 5.1.11.2, “DNS Lookups and the Host Cache”.

--skip-innodb

Disable the InnoDB storage engine. In this case, because the default storage engine is InnoDB, the server cannot start unless you also use --default-storage-engine and --default-tmp-storage-engine to set the default to some other engine for both permanent and TEMPORARY tables.

The InnoDB storage engine cannot be disabled, and the --skip-innodb option is deprecated and has no effect. Its use results in a warning. Expect this option to be removed in a future release of MySQL.

--skip-new

This option disables (what used to be considered) new, possibly unsafe behaviors. It results in these settings: delay_key_write=OFF, concurrent_insert=NEVER, automatic_sp_privileges=OFF. It also causes OPTIMIZE TABLE to be mapped to ALTER TABLE for storage engines for which OPTIMIZE TABLE is not supported.

--skip-partition

Disables user-defined partitioning. Partitioned tables can be seen using SHOW TABLES or by querying the Information Schema TABLES table, but cannot be created or modified, nor can data in such tables be accessed. All partition-specific columns in the Information Schema PARTITIONS table display NULL.

Since DROP TABLE removes table definition (.frm) files, this statement works on partitioned tables even when partitioning is disabled using the option. The statement, however, does not remove partition definitions associated with partitioned tables in such cases. For this reason, you should avoid dropping partitioned tables with partitioning disabled, or take action to remove orphaned .par files manually (if present).

This option is deprecated in MySQL 5.7.16, and is removed from MySQL 8.0 because in MySQL 8.0, the partitioning engine is replaced by native partitioning, which cannot be disabled.

--skip-show-database

This option sets the skip_show_database system variable that controls who is permitted to use the SHOW DATABASES statement. See Section 5.1.7, “Server System Variables”.

--skip-stack-trace

Do not write stack traces. This option is useful when you are running mysqld under a debugger. On some systems, you also must use this option to get a core file. See Section 5.8, “Debugging MySQL”.

--slow-start-timeout=timeout

This option controls the Windows service control manager's service start timeout. The value is the maximum number of milliseconds that the service control manager waits before trying to kill the windows service during startup. The default value is 15000 (15 seconds). If the MySQL service takes too long to start, you may need to increase this value. A value of 0 means there is no timeout.

--socket=path

On Unix, this option specifies the Unix socket file to use when listening for local connections. The default value is /tmp/mysql.sock. If this option is given, the server creates the file in the data directory unless an absolute path name is given to specify a different directory. On Windows, the option specifies the pipe name to use when listening for local connections that use a named pipe. The default value is MySQL (not case-sensitive).

--sql-mode=value[,value[,value...]]

Set the SQL mode. See Section 5.1.10, “Server SQL Modes”.

--ssl, --skip-ssl

The --ssl option specifies that the server permits but does not require encrypted connections. This option is enabled by default.

--ssl can be specified in negated form as --skip-ssl or a synonym (--ssl=OFF, --disable-ssl). In this case, the option specifies that the server does not permit encrypted connections, regardless of the settings of the tls_xxx and ssl_xxx system variables.

For more information about configuring whether the server permits clients to connect using SSL and indicating where to find SSL keys and certificates, see Section 6.3.1, “Configuring MySQL to Use Encrypted Connections”, which also describes server capabilities for certificate and key file autogeneration and autodiscovery. Consider setting at least the ssl_cert and ssl_key system variables on the server side and the --ssl-ca (or --ssl-capath) option on the client side.

--standalone

Available on Windows only; instructs the MySQL server not to run as a service.

--super-large-pages

Standard use of large pages in MySQL attempts to use the largest size supported, up to 4MB. Under Solaris, a “super large pages” feature enables uses of pages up to 256MB. This feature is available for recent SPARC platforms. It can be enabled or disabled by using the --super-large-pages or --skip-super-large-pages option.

--symbolic-links, --skip-symbolic-links

Enable or disable symbolic link support. On Unix, enabling symbolic links means that you can link a MyISAM index file or data file to another directory with the INDEX DIRECTORY or DATA DIRECTORY option of the CREATE TABLE statement. If you delete or rename the table, the files that its symbolic links point to also are deleted or renamed. See Section 8.12.3.2, “Using Symbolic Links for MyISAM Tables on Unix”.

This option has no meaning on Windows.

--sysdate-is-now

SYSDATE() by default returns the time at which it executes, not the time at which the statement in which it occurs begins executing. This differs from the behavior of NOW(). This option causes SYSDATE() to be a synonym for NOW(). For information about the implications for binary logging and replication, see the description for SYSDATE() in Section 12.7, “Date and Time Functions” and for SET TIMESTAMP in Section 5.1.7, “Server System Variables”.

--tc-heuristic-recover={COMMIT|ROLLBACK}

The decision to use in a manual heuristic recovery.

If a --tc-heuristic-recover option is specified, the server exits regardless of whether manual heuristic recovery is successful.

On systems with more than one storage engine capable of two-phase commit, the ROLLBACK option is not safe and causes recovery to halt with the following error:

[ERROR] --tc-heuristic-recover rollback strategy is not safe on systems with more than one 2-phase-commit-capable storage engine. Aborting crash recovery.

--temp-pool

This option is ignored except on Linux. On Linux, it causes most temporary files created by the server to use a small set of names, rather than a unique name for each new file. This works around a problem in the Linux kernel dealing with creating many new files with different names. With the old behavior, Linux seems to “leak” memory, because it is being allocated to the directory entry cache rather than to the disk cache.

As of MySQL 5.7.18, this option is deprecated and is removed in MySQL 8.0.

--transaction-isolation=level

Sets the default transaction isolation level. The level value can be READ-UNCOMMITTED, READ-COMMITTED, REPEATABLE-READ, or SERIALIZABLE. See Section 13.3.6, “SET TRANSACTION Statement”.

The default transaction isolation level can also be set at runtime using the SET TRANSACTION statement or by setting the tx_isolation (or, as of MySQL 5.7.20, transaction_isolation) system variable.

--transaction-read-only

Sets the default transaction access mode. By default, read-only mode is disabled, so the mode is read/write.

To set the default transaction access mode at runtime, use the SET TRANSACTION statement or set the tx_read_only (or, as of MySQL 5.7.20, transaction_read_only) system variable. See Section 13.3.6, “SET TRANSACTION Statement”.

--tmpdir=dir_name, -t dir_name

The path of the directory to use for creating temporary files. It might be useful if your default /tmp directory resides on a partition that is too small to hold temporary tables. This option accepts several paths that are used in round-robin fashion. Paths should be separated by colon characters (:) on Unix and semicolon characters (;) on Windows.

--tmpdir can be a non-permanent location, such as a directory on a memory-based file system or a directory that is cleared when the server host restarts. If the MySQL server is acting as a replica, and you are using a non-permanent location for --tmpdir, consider setting a different temporary directory for the replica using the slave_load_tmpdir system variable. For a replication replica, the temporary files used to replicate LOAD DATA statements are stored in this directory, so with a permanent location they can survive machine restarts, although replication can now continue after a restart if the temporary files have been removed.

For more information about the storage location of temporary files, see Section B.3.3.5, “Where MySQL Stores Temporary Files”.

--user={user_name|user_id}, -u {user_name|user_id}

Run the mysqld server as the user having the name user_name or the numeric user ID user_id. (“User” in this context refers to a system login account, not a MySQL user listed in the grant tables.)

This option is mandatory when starting mysqld as root. The server changes its user ID during its startup sequence, causing it to run as that particular user rather than as root. See Section 6.1.1, “Security Guidelines”.

To avoid a possible security hole where a user adds a --user=root option to a my.cnf file (thus causing the server to run as root), mysqld uses only the first --user option specified and produces a warning if there are multiple --user options. Options in /etc/my.cnf and $MYSQL_HOME/my.cnf are processed before command-line options, so it is recommended that you put a --user option in /etc/my.cnf and specify a value other than root. The option in /etc/my.cnf is found before any other --user options, which ensures that the server runs as a user other than root, and that a warning results if any other --user option is found.

--validate-user-plugins[={OFF|ON}]

If this option is enabled (the default), the server checks each user account and produces a warning if conditions are found that would make the account unusable:

Enabling --validate-user-plugins slows down server initialization and FLUSH PRIVILEGES. If you do not require the additional checking, you can disable this option at startup to avoid the performance decrement.

--verbose, -v

Use this option with the --help option for detailed help.

--version, -V

Display version information and exit.