When you start the mysqld server, you can specify program options using any of the methods described in Section 4.2.3, “Specifying Program Options”. The most common methods are to provide options in an option file or on the command line. However, in most cases it is desirable to make sure that the server uses the same options each time it runs. The best way to ensure this is to list them in an option file. See Section 4.2.3.3, “Using Option Files”.
MySQL Enterprise. For expert advice on setting command options, subscribe to the MySQL Enterprise Monitor. For more information, see http://www.mysql.com/products/enterprise/advisors.html.
mysqld reads options from the
[mysqld]
and [server]
groups. mysqld_safe reads options from the
[mysqld]
, [server]
,
[mysqld_safe]
, and
[safe_mysqld]
groups.
mysql.server reads options from the
[mysqld]
and [mysql.server]
groups.
An embedded MySQL server usually reads options from the
[server]
, [embedded]
, and
[
groups, where xxxxx
_SERVER]xxxxx
is the name of the
application into which the server is embedded.
mysqld accepts many command options. For a brief summary, execute mysqld --help. To see the full list, use mysqld --verbose --help.
The following list shows some of the most common server options. Additional options are described in other sections:
Options that affect security: See Section 5.3.4, “Security-Related mysqld Options”.
SSL-related options: See Section 5.5.6.3, “SSL Command Options”.
Binary log control options: See Section 5.2.4, “The Binary Log”.
Replication-related options: See Section 16.1.3, “Replication and Binary Logging Options and Variables”.
Options for loading plugins such as pluggable storage engines: See Section 5.1.3, “Server Options for Loading Plugins”.
Options specific to particular storage engines: See
Section 13.5.1, “MyISAM
Startup Options”, and
Section 13.6.3, “InnoDB
Startup Options and System Variables”.
You can also set the values of server system variables by using variable names as options, as described at the end of this section.
Some options control the size of buffers or caches. For a given buffer, the server might need to allocate internal data structures. These structures typically are allocated from the total memory allocated to the buffer, and the amount of space required might be platform dependent. This means that when you assign a value to an option that controls a buffer size, the amount of space actually available might differ from the value assigned. In some cases, the amount might be less than the value assigned. It is also possible that the server will adjust a value upward. For example, if you assign a value of 0 to an option for which the minimal value is 1024, the server will set the value to 1024.
Values for buffer sizes, lengths, and stack sizes are given in bytes unless otherwise specified.
Some options take file name values. Unless otherwise specified,
the default file location is the data directory if the value is a
relative path name. To specify the location explicitly, use an
absolute path name. Suppose that the data directory is
/var/mysql/data
. If a file-valued option is
given as a relative path name, it will be located under
/var/mysql/data
. If the value is an absolute
path name, its location is as given by the path name.
--help
, -?
Command-Line Format | -? |
|
Config-File Format | help |
Display a short help message and exit. Use both the
--verbose
and
--help
options to see the full
message.
Command-Line Format | --allow-suspicious-udfs |
|
Config-File Format | allow-suspicious-udfs |
|
Permitted Values | ||
Type | boolean |
|
Default | FALSE |
This option controls whether user-defined functions that have
only an xxx
symbol for the main function
can be loaded. By default, the option is off and only UDFs
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 UDFs. See
Section 22.3.2.6, “User-Defined Function Security Precautions”.
Command-Line Format | --ansi |
|
Config-File Format | 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 1.8.3, “Running MySQL in ANSI Mode”, and
Section 5.1.8, “Server SQL Modes”.
Command-Line Format | --basedir=name |
|
Config-File Format | basedir |
|
Option Sets Variable | Yes, basedir
|
|
Variable Name | basedir |
|
Variable Scope | Global | |
Dynamic Variable | No | |
Permitted Values | ||
Type | filename |
The path to the MySQL installation directory. All paths are usually resolved relative to this directory.
Command-Line Format | --big-tables |
|
Config-File Format | big-tables |
|
Option Sets Variable | Yes, big_tables
|
|
Variable Name | big-tables |
|
Variable Scope | Session | |
Dynamic Variable | Yes | |
Permitted Values | ||
Type | boolean |
Allow large result sets by saving all temporary sets in files. This option prevents most “table full” errors, but also slows down queries for which in-memory tables would suffice. Since MySQL 3.23.2, the server is able to handle large result sets automatically by using memory for small temporary tables and switching to disk tables where necessary.
Command-Line Format | --bind-address=name |
|
Config-File Format | bind-address |
|
Permitted Values | ||
Type | string |
|
Default | 0.0.0.0 |
|
Range | 0.0.0.0-255.255.255.255 |
The IP address to bind to. Only one address can be selected. If this option is specified multiple times, the last address given is used.
If no address or 0.0.0.0
is specified, the
server listens on all interfaces.
--binlog-format={ROW|STATEMENT|MIXED}
Command-Line Format | --binlog-format |
|
Config-File Format | binlog-format |
|
Option Sets Variable | Yes, binlog_format
|
|
Variable Name | binlog_format |
|
Variable Scope | Both | |
Dynamic Variable | Yes | |
Permitted Values | ||
Type | enumeration |
|
Default | STATEMENT |
|
Valid Values |
ROW , STATEMENT , MIXED
|
Specify whether to use row-based, statement-based, or mixed replication. Statement-based is the default in MySQL 5.5. See Section 16.1.2, “Replication Formats”.
Previous to MySQL 5.5, setting the binary logging format
without enabling binary logging prevented the MySQL server
from starting. In MySQL 5.5, the server starts in
such cases, the binlog_format
global system
variable is set, and a warning is logged instead of an error.
(Bug#42928)
Command-Line Format | --bootstrap |
|
Config-File Format | bootstrap |
This option is used by the mysql_install_db script to create the MySQL privilege tables without having to start a full MySQL server.
This option is unavailable if MySQL was configured with the
--disable-grant-options
option. See Section 2.10.2, “Typical configure Options”.
Command-Line Format | --character-sets-dir=name |
|
Config-File Format | character-sets-dir |
|
Option Sets Variable | Yes, character_sets_dir
|
|
Variable Name | character-sets-dir |
|
Variable Scope | Global | |
Dynamic Variable | No | |
Permitted Values | ||
Type | filename |
The directory where character sets are installed. See Section 9.5, “Character Set Configuration”.
--character-set-client-handshake
Command-Line Format | --character-set-client-handshake |
|
Config-File Format | character-set-client-handshake |
|
Permitted Values | ||
Type | boolean |
|
Default | TRUE |
Don't 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.
--character-set-filesystem=
charset_name
Command-Line Format | --character-set-filesystem=name |
|
Config-File Format | character-set-filesystem |
|
Option Sets Variable | Yes, character_set_filesystem
|
|
Variable Name | character_set_filesystem |
|
Variable Scope | Both | |
Dynamic Variable | Yes | |
Permitted Values | ||
Type | string |
The file system character set. This option sets the
character_set_filesystem
system variable.
--character-set-server=
,
charset_name
-C
charset_name
Command-Line Format | --character-set-server |
|
Config-File Format | character-set-server |
|
Option Sets Variable | Yes, character_set_server
|
|
Variable Name | character_set_server |
|
Variable Scope | Both | |
Dynamic Variable | Yes | |
Permitted Values | ||
Type | string |
Use charset_name
as the default
server character set. See
Section 9.5, “Character Set Configuration”. If you use this
option to specify a nondefault character set, you should also
use --collation-server
to
specify the collation.
--chroot=
,
path
-r
path
Command-Line Format | --chroot=name |
|
Config-File Format | chroot |
|
Permitted Values | ||
Type | filename |
Put the mysqld server in a closed
environment during startup by using the
chroot()
system call. This is a recommended
security measure. Note that use of this option somewhat limits
LOAD DATA
INFILE
and
SELECT ... INTO
OUTFILE
.
--collation-server=
collation_name
Command-Line Format | --collation-server |
|
Config-File Format | collation-server |
|
Option Sets Variable | Yes, collation_server
|
|
Variable Name | collation_server |
|
Variable Scope | Both | |
Dynamic Variable | Yes | |
Permitted Values | ||
Type | string |
Use collation_name
as the default
server collation. See Section 9.5, “Character Set Configuration”.
Command-Line Format | --console |
|
Config-File Format | console |
|
Platform Specific | windows |
(Windows only.) Write error log messages to
stderr
and stdout
even
if --log-error
is specified.
mysqld does not close the console window if
this option is used.
Command-Line Format | --core-file |
|
Config-File Format | core-file |
|
Permitted Values | ||
Type | boolean |
|
Default | FALSE |
Write a core file if mysqld dies. The name
and location of the core file is system dependent. On Linux, a
core file named
core.
is
written to the current working directory of the process, which
for mysqld is the data directory.
pid
pid
represents the process ID of
the server process. On Mac OS X, a core file named
core.
is
written to the pid
/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.
--datadir=
,
path
-h
path
Command-Line Format | --datadir=name |
|
Config-File Format | datadir |
|
Option Sets Variable | Yes, datadir
|
|
Variable Name | datadir |
|
Variable Scope | Global | |
Dynamic Variable | No | |
Permitted Values | ||
Type | filename |
The path to the data directory.
--debug[=
,
debug_options
]-# [
debug_options
]
Command-Line Format | --debug[=debug_options] |
|
Config-File Format | debug |
|
Variable Name | debug |
|
Variable Scope | Both | |
Dynamic Variable | Yes | |
Permitted Values | ||
Type | string |
|
Default | 'd:t:o,/tmp/mysqld.trace' |
If MySQL is configured with
--with-debug
, you can use
this option to get a trace file of what
mysqld is doing. A typical
debug_options
string is
'd:t:o,
.
The default is file_name
''d:t:i:o,mysqld.trace'
. See
MySQL
Internals: Porting.
Using --with-debug
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
.
Command-Line Format | --debug-sync-timeout[=#] |
|
Config-File Format | debug-sync-timeout |
|
Permitted Values | ||
Type | numeric |
Controls whether the Debug Sync facility for testing and
debugging is enabled. Use of Debug Sync requires that MySQL be
configured with the
--enable-debug-sync
option
(see Section 2.10.2, “Typical configure 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-character-set=
charset_name
Command-Line Format | --default-character-set=name |
|
Config-File Format | default-character-set |
|
Deprecated | 5.0 | |
Permitted Values | ||
Type | string |
Use charset_name
as the default
character set. This option is deprecated in favor of
--character-set-server
. See
Section 9.5, “Character Set Configuration”.
--default-character-set
was
removed in MySQL 5.5.3.
--default-collation=
collation_name
Command-Line Format | --default-collation=name |
|
Variable Name | default-collation |
|
Variable Scope | ||
Dynamic Variable | No | |
Deprecated | 4.1.3 | |
Permitted Values | ||
Type | string |
Use collation_name
as the default
collation. This option is deprecated in favor of
--collation-server
. See
Section 9.5, “Character Set Configuration”.
--default-collation
was removed
in MySQL 5.5.3.
Command-Line Format | --default-storage-engine=name |
|
Config-File Format | default-storage-engine |
Set the default storage engine (table type) for tables. See Chapter 13, Storage Engines.
Command-Line Format | --default-time-zone=name |
|
Config-File Format | default-time-zone |
|
Permitted Values | ||
Type | string |
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.
--delay-key-write[={OFF|ON|ALL}]
Command-Line Format | --delay-key-write[=name] |
|
Config-File Format | delay-key-write |
|
Option Sets Variable | Yes, delay_key_write
|
|
Variable Name | delay-key-write |
|
Variable Scope | Global | |
Dynamic Variable | Yes | |
Permitted Values | ||
Type | enumeration |
|
Default | ON |
|
Valid Values |
ON , OFF , ALL
|
Specify how to use delayed key writes. Delayed key writing
causes key buffers not to be flushed between writes for
MyISAM
tables. OFF
disables delayed key writes. ON
enables
delayed key writes for those tables that were created with the
DELAY_KEY_WRITE
option.
ALL
delays key writes for all
MyISAM
tables. See
Section 7.5.3, “Tuning Server Parameters”, and
Section 13.5.1, “MyISAM
Startup Options”.
If you set this variable to ALL
, you
should not use MyISAM
tables from within
another program (such as another MySQL server or
myisamchk) when the tables are in use.
Doing so leads to index corruption.
Command-Line Format | --des-key-file=name |
|
Config-File Format | des-key-file |
Read the default DES keys from this file. These keys are used
by the DES_ENCRYPT()
and
DES_DECRYPT()
functions.
Command-Line Format | --named_pipe |
|
Config-File Format | enable-named-pipe |
|
Platform Specific | windows |
Enable support for named pipes. This option applies only on Windows NT, 2000, XP, and 2003 systems.
Command-Line Format | --enable-pstack |
|
Config-File Format | enable-pstack |
|
Permitted Values | ||
Type | boolean |
|
Default | FALSE |
Print a symbolic stack trace on failure. This capability is
available only on Intel Linux systems, and only if MySQL was
configured with the --with-pstack
option.
--engine-condition-pushdown={ON|OFF}
Command-Line Format | --engine-condition-pushdown |
|
Config-File Format | engine-condition-pushdown |
|
Option Sets Variable | Yes, engine_condition_pushdown
|
|
Variable Name | engine_condition_pushdown |
|
Variable Scope | Both | |
Dynamic Variable | Yes | |
Permitted Values | ||
Type | boolean |
|
Default | ON |
Sets the
engine_condition_pushdown
system variable. For more information, see
Section 7.2.7, “Condition Pushdown Optimization”.
Command-Line Format | --event-scheduler[=value] |
|
Config-File Format | event-scheduler |
|
Option Sets Variable | Yes, event_scheduler
|
|
Variable Name | event_scheduler |
|
Variable Scope | Global | |
Dynamic Variable | Yes | |
Permitted Values | ||
Type | enumeration |
|
Default | OFF |
|
Valid Values |
ON , OFF , DISABLED
|
Enable or disable, and start or stop, the event scheduler.
For detailed information, see
The
--event-scheduler
Option.
--exit-info[=
,
flags
]-T [
flags
]
Command-Line Format | --exit-info[=flags] |
|
Config-File Format | exit-info |
|
Permitted Values | ||
Type | numeric |
This is a bit mask of different flags that you can use for debugging the mysqld server. Do not use this option unless you know exactly what it does!
Command-Line Format | --external-locking |
|
Config-File Format | external-locking |
|
Option Sets Variable | Yes, skip_external_locking
|
|
Disabled by | skip-external-locking |
|
Permitted Values | ||
Type | boolean |
|
Default | FALSE |
Enable external locking (system locking), which is disabled by
default as of MySQL 4.0. Note that 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.
For more information about external locking, including conditions under which it can and cannot be used, see Section 7.3.5, “External Locking”.
Command-Line Format | --flush |
|
Config-File Format | flush |
|
Variable Name | flush |
|
Variable Scope | Global | |
Dynamic Variable | Yes | |
Permitted Values | ||
Type | boolean |
|
Default | OFF |
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.5.4.2, “What to Do If MySQL Keeps Crashing”.
Command-Line Format | --gdb |
|
Config-File Format | gdb |
|
Permitted Values | ||
Type | boolean |
|
Default | FALSE |
Install an interrupt handler for SIGINT
(needed to stop mysqld with
^C
to set breakpoints) and disable stack
tracing and core file handling. See
MySQL
Internals: Porting.
Command-Line Format | --general-log |
|
Config-File Format | general-log |
|
Option Sets Variable | Yes, general_log
|
|
Variable Name | general_log |
|
Variable Scope | Global | |
Dynamic Variable | Yes | |
Permitted Values | ||
Type | boolean |
|
Default | OFF |
Specify the initial general query log state. With no argument
or an argument of 1, the
--general-log
option enables
the log. If omitted or given with an argument of 0, the option
disables the log.
Command-Line Format | --init-file=name |
|
Config-File Format | init-file |
|
Option Sets Variable | Yes, init_file
|
|
Variable Name | init_file |
|
Variable Scope | Global | |
Dynamic Variable | No | |
Permitted Values | ||
Type | filename |
Read SQL statements from this file at startup. Each statement must be on a single line and should not include comments.
This option is unavailable if MySQL was configured with the
--disable-grant-options
option. See Section 2.10.2, “Typical configure Options”.
--innodb-
xxx
The InnoDB
options are listed in
Section 13.6.3, “InnoDB
Startup Options and System Variables”.
--language=
lang_name
,
-L lang_name
Version Deprecated | 5.5.0 | |
Command-Line Format | --language=name |
|
Config-File Format | language |
|
Option Sets Variable | Yes, language
|
|
Variable Name | language |
|
Variable Scope | Global | |
Dynamic Variable | No | |
Deprecated | 5.5.0, by lc-messages-dir
|
|
Permitted Values | ||
Type | filename |
|
Default | /usr/local/mysql/share/mysql/english/ |
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 9.2, “Setting the Error Message Language”.
As of MySQL 5.5,
--lc-messages-dir
and
--lc-messages
should be used
rather than --language
, which
is deprecated and handled as an alias for
--lc-messages-dir
.
Command-Line Format | --large-pages |
|
Config-File Format | large-pages |
|
Option Sets Variable | Yes, large_pages
|
|
Variable Name | large_pages |
|
Variable Scope | Global | |
Dynamic Variable | No | |
Platform Specific | linux | |
Permitted Values | ||
Type (linux) | boolean |
|
Default | FALSE |
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 5.5 supports the Linux implementation of
large page support (which is called HugeTLB in Linux). See
Section 7.5.9, “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.
Command-Line Format | --lc-messages=name |
|
Config-File Format | lc-messages |
|
Option Sets Variable | Yes, lc_messages
|
|
Variable Name | lc-messages |
|
Variable Scope | Both | |
Dynamic Variable | Yes | |
Permitted Values | ||
Type | string |
The locale to use for error messages. The server converts the
argument to a language name and combines it with the value of
the --lc-messages-dir
to produce the location
for the error message file. See
Section 9.2, “Setting the Error Message Language”.
Command-Line Format | --lc-messages-dir=path |
|
Config-File Format | lc-messages-dir |
|
Option Sets Variable | Yes, lc_messages_dir
|
|
Variable Name | lc-messages-dir |
|
Variable Scope | Global | |
Dynamic Variable | No | |
Permitted Values | ||
Type | string |
The directory where error messages are located. The value is
used together with the value of
--lc-messages-dir
to produce the location for
the error message file. See
Section 9.2, “Setting the Error Message Language”.
--log[=
,
file_name
]-l [
file_name
]
Command-Line Format | --log[=name] |
|
Config-File Format | log |
|
Option Sets Variable | Yes, log
|
|
Variable Name | log |
|
Variable Scope | Global | |
Dynamic Variable | Yes | |
Deprecated | 5.1.29, by general-log
|
|
Permitted Values | ||
Type | string |
|
Default | OFF |
This option enables logging to the general query log, which
contains entries that record client connections and SQL
statements received from clients. The log output destination
can be selected with the
--log-output
option. If you
omit the file name, MySQL uses
as the file name. See Section 5.2.1, “Selecting General Query and Slow Query Log Output Destinations”, and
Section 5.2.3, “The General Query Log”.
host_name
.log
The --log
option is deprecated
and will be removed (along with the
log
system variable) in MySQL
7.0. Instead, use the
--general_log
option to enable
the general query log and the
--general_log_file=
option to set the general query log file name.
file_name
Command-Line Format | --log-error[=name] |
|
Config-File Format | log-error |
|
Option Sets Variable | Yes, log_error
|
|
Variable Name | log_error |
|
Variable Scope | Global | |
Dynamic Variable | No | |
Permitted Values | ||
Type | filename |
Log errors and startup messages to this file. See
Section 5.2.2, “The Error Log”. If you omit the file name, MySQL
uses
.
If the file name has no extension, the server adds an
extension of host_name
.err.err
.
Command-Line Format | --log-isam[=name] |
|
Config-File Format | log-isam |
|
Permitted Values | ||
Type | filename |
Log all MyISAM
changes to this file (used
only when debugging MyISAM
).
Command-Line Format | --log-long-format |
|
Config-File Format | log-long-format |
|
Deprecated | 4.1 |
Log extra information to the binary log and slow query log, if
they have been activated. For example, the user name and
timestamp are logged for all queries. This option is
deprecated, as it now represents the default logging behavior.
(See the description for
--log-short-format
.) The
--log-queries-not-using-indexes
option is available for the purpose of logging queries that do
not use indexes to the slow query log.
--log-long-format
was removed
in MySQL 5.5.3.
Command-Line Format | --log-output[=name] |
|
Config-File Format | log-output |
|
Option Sets Variable | Yes, log_output
|
|
Variable Name | log_output |
|
Variable Scope | Global | |
Dynamic Variable | Yes | |
Permitted Values | ||
Type | set |
|
Default | FILE |
|
Valid Values |
TABLE , FILE , NONE
|
This option determines the destination for general query log
and slow query log output. The option value can be given as
one or more of the words TABLE
,
FILE
, or NONE
. If the
option is given without a value, the default is
FILE
. TABLE
select
logging to the general_log
and slow_log
tables in the
mysql
database as a destination.
FILE
selects logging to log files as a
destination. NONE
disables logging. If
NONE
is present in the option value, it
takes precedence over any other words that are present.
TABLE
and FILE
can both
be given to select to both log output destinations.
This option selects log output destinations, but does not
enable log output. To do that, use the
--general_log
and
--slow_query_log
options. For
FILE
logging, the
--general_log_file
and
-slow_query_log_file
options determine the
log file location. For more information, see
Section 5.2.1, “Selecting General Query and Slow Query Log Output Destinations”.
--log-queries-not-using-indexes
Command-Line Format | --log-queries-not-using-indexes |
|
Config-File Format | log-queries-not-using-indexes |
|
Option Sets Variable | Yes, log_queries_not_using_indexes
|
|
Variable Name | log_queries_not_using_indexes |
|
Variable Scope | Global | |
Dynamic Variable | Yes | |
Permitted Values | ||
Type | boolean |
If you are using this option with the slow query log enabled, queries that are expected to retrieve all rows are logged. See Section 5.2.5, “The Slow Query Log”. This option does not necessarily mean that no index is used. For example, a query that uses a full index scan uses an index but would be logged because the index would not limit the number of rows.
Command-Line Format | --log-short-format |
|
Config-File Format | log-short-format |
|
Permitted Values | ||
Type | boolean |
|
Default | FALSE |
Originally intended to log less information to the binary log and slow query log, if they have been activated. However, this option is not operational.
Command-Line Format | --log-slow-admin-statements |
|
Config-File Format | log-slow-admin-statements |
|
Permitted Values | ||
Type | boolean |
|
Default | FALSE |
Log slow administrative statements such as
OPTIMIZE TABLE
,
ANALYZE TABLE
, and
ALTER TABLE
to the slow query
log.
--log-slow-queries[=
file_name
]
Command-Line Format | --log-slow-queries[=name] |
|
Config-File Format | log-slow-queries |
|
Option Sets Variable | Yes, log_slow_queries
|
|
Variable Name | log_slow_queries |
|
Variable Scope | Global | |
Dynamic Variable | Yes | |
Deprecated | 5.1.29, by slow-query-log
|
|
Permitted Values | ||
Type | boolean |
This option enables logging to the slow query log, which
contains entries for all queries that have taken more than
long_query_time
seconds to
execute. See the descriptions of the
--log-long-format
and
--log-short-format
options for
details. The log output destination can be selected with the
--log-output
option. If you
omit the file name, MySQL uses
as the file name. See Section 5.2.1, “Selecting General Query and Slow Query Log Output Destinations”, and
Section 5.2.5, “The Slow Query Log”.
host_name
-slow.log
The --log-slow-queries
option
is deprecated and will be removed (along with the
log_slow_queries
system
variable) in MySQL 7.0. Instead, use the
--slow_query_log
option to
enable the slow query log and the
--slow_query_log_file=
option to set the slow query log file name.
file_name
Command-Line Format | --log-tc=name |
|
Config-File Format | log-tc |
|
Permitted Values | ||
Type | filename |
|
Default | tc.log |
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. Currently,
this option is unused.
Command-Line Format | --log-tc-size=# |
|
Config-File Format | log-tc-size |
|
Permitted Values | ||
Platform Bit Size | 32 |
|
Type | numeric |
|
Default | 24576 |
|
Max Value | 4294967295 |
|
Permitted Values | ||
Platform Bit Size | 64 |
|
Type | numeric |
|
Default | 24576 |
|
Max Value | 18446744073709547520 |
The size in bytes of the memory-mapped transaction coordinator log. The default size is 24KB.
--log-warnings[=
,
level
]-W [
level
]
Command-Line Format | --log-warnings[=#] |
|
Config-File Format | log-warnings |
|
Option Sets Variable | Yes, log_warnings
|
|
Variable Name | log_warnings |
|
Variable Scope | Both | |
Dynamic Variable | Yes | |
Disabled by | skip-log-warnings |
|
Permitted Values | ||
Platform Bit Size | 64 |
|
Type | numeric |
|
Default | 1 |
|
Range | 0-18446744073709547520 |
Print out warnings such as Aborted
connection...
to the error log. Enabling this option
is recommended, for example, if you use replication (you get
more information about what is happening, such as messages
about network failures and reconnections). This option is
enabled (1) by default, and the default
level
value if omitted is 1. To
disable this option, use
--log-warnings=0
. If the value
is greater than 1, aborted connections are written to the
error log, and access-denied errors for new connection
attempts are written. See
Section B.5.2.11, “Communication Errors and Aborted Connections”.
If a slave server was started with
--log-warnings
enabled, the
slave prints messages to the error log to provide information
about its status, such as the binary log and relay log
coordinates where it starts its job, when it is switching to
another relay log, when it reconnects after a disconnect, and
so forth. The server logs messages about statements that are
unsafe for statement-based logging only if
--log-warnings
is enabled.
Command-Line Format | --low-priority-updates |
|
Config-File Format | low-priority-updates |
|
Option Sets Variable | Yes, low_priority_updates
|
|
Variable Name | low_priority_updates |
|
Variable Scope | Both | |
Dynamic Variable | Yes | |
Permitted Values | ||
Type | boolean |
|
Default | FALSE |
Give table-modifying operations
(INSERT
,
REPLACE
,
DELETE
,
UPDATE
) lower priority than
selects. This can also be done via {INSERT | REPLACE
| DELETE | UPDATE} LOW_PRIORITY ...
to lower the
priority of only one query, or by SET
LOW_PRIORITY_UPDATES=1
to change the priority in one
thread. This affects only storage engines that use only
table-level locking (MyISAM
,
MEMORY
, MERGE
). See
Section 7.3.2, “Table Locking Issues”.
--min-examined-row-limit=
number
Command-Line Format | --min-examined-row-limit=# |
|
Config-File Format | min-examined-row-limit |
|
Variable Name | min_examined_row_limit |
|
Variable Scope | Both | |
Dynamic Variable | Yes | |
Permitted Values | ||
Platform Bit Size | 32 |
|
Type | numeric |
|
Default | 0 |
|
Range | 0-4294967295 |
|
Permitted Values | ||
Platform Bit Size | 64 |
|
Type | numeric |
|
Default | 0 |
|
Range | 0-18446744073709547520 |
When this option is set, queries which examine fewer than
number
rows are not written to the
slow query log. The default is 0.
Command-Line Format | --memlock |
|
Config-File Format | memlock |
|
Variable Name | locked_in_memory |
|
Variable Scope | Global | |
Dynamic Variable | No | |
Permitted Values | ||
Type | boolean |
|
Default | FALSE |
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 as well as most Linux distributions that use
a 2.4 or newer kernel. 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:
shell> 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;
Using this option requires that you run the server as
root
, which, for reasons of security, is
normally not a good idea. See
Section 5.3.6, “How to Run MySQL as a Normal User”.
You must not try to use this option on a system that does
not support the mlockall()
system call;
if you do so, mysqld will very likely
crash as soon as you try to start it.
Command-Line Format | --myisam-block-size=# |
|
Config-File Format | myisam-block-size |
|
Permitted Values | ||
Type | numeric |
|
Default | 1024 |
|
Range | 1024-16384 |
The block size to be used for MyISAM
index
pages.
--myisam-recover[=
option
[,option
]...]]
Command-Line Format | --myisam-recover[=name] |
|
Config-File Format | myisam-recover |
|
Permitted Values | ||
Type | enumeration |
|
Default | OFF |
|
Valid Values |
DEFAULT , BACKUP , FORCE , QUICK
|
Set the MyISAM
storage engine recovery
mode. The option value is any combination of the values of
DEFAULT
, BACKUP
,
FORCE
, or QUICK
. If you
specify multiple values, separate them by commas. Specifying
the option with no argument is the same as specifying
DEFAULT
, and specifying with an explicit
value of ""
disables recovery (same as not
giving the option). If recovery is enabled, each time
mysqld opens a MyISAM
table, it checks whether the table is marked as crashed or
wasn't closed properly. (The last option works only if you are
running with external locking disabled.) If this is the case,
mysqld runs a check on the table. If the
table was corrupted, mysqld attempts to
repair it.
The following options affect how the repair works.
Option | Description |
DEFAULT |
Recovery without backup, forcing, or quick checking. |
BACKUP |
If the data file was changed during recovery, save a backup of the
file as
. |
FORCE |
Run recovery even if we would lose more than one row from the
.MYD file. |
QUICK |
Don't check the rows in the table if there aren't any delete blocks. |
Before the server automatically repairs a table, it writes a
note about the repair to the error log. If you want to be able
to recover from most problems without user intervention, you
should use the options BACKUP,FORCE
. This
forces a repair of a table even if some rows would be deleted,
but it keeps the old data file as a backup so that you can
later examine what happened.
Command-Line Format | --old-alter-table |
|
Config-File Format | old-alter-table |
|
Option Sets Variable | Yes, old_alter_table
|
|
Variable Name | old-alter-table |
|
Variable Scope | Both | |
Dynamic Variable | Yes | |
Permitted Values | ||
Type | boolean |
|
Default | OFF |
When this option is given, the server does not use the
optimized method of processing an ALTER
TABLE
operation. It reverts to using a temporary
table, copying over the data, and then renaming the temporary
table to the original, as used by MySQL 5.0 and earlier. For
more information on the operation of
ALTER TABLE
, see
Section 12.1.6, “ALTER TABLE
Syntax”.
Command-Line Format | --old_passwords |
|
Config-File Format | old-passwords |
|
Option Sets Variable | Yes, old_passwords
|
|
Variable Name | old_passwords |
|
Variable Scope | Both | |
Dynamic Variable | Yes | |
Permitted Values | ||
Type | boolean |
|
Default | FALSE |
Force the server to generate short (pre-4.1) password hashes for new passwords. This is useful for compatibility when the server must support older client programs. See Section 5.3.2.3, “Password Hashing in MySQL”.
Command-Line Format | --old-style-user-limits |
|
Config-File Format | old-style-user-limits |
|
Permitted Values | ||
Type | boolean |
|
Default | FALSE |
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 5.5.4, “Setting Account Resource Limits”.
Command-Line Format | --one-thread |
|
Config-File Format | one-thread |
Only use one thread (for debugging under Linux). This option is available only if the server is built with debugging enabled. See MySQL Internals: Porting.
This option is deprecated; use
--thread_handling=no-threads
instead.
Command-Line Format | --open-files-limit=# |
|
Config-File Format | open-files-limit |
|
Option Sets Variable | Yes, open_files_limit
|
|
Variable Name | open_files_limit |
|
Variable Scope | Global | |
Dynamic Variable | No | |
Permitted Values | ||
Type | numeric |
|
Default | 0 |
|
Range | 0-65535 |
Changes the number of file descriptors available to
mysqld. You should try increasing the value
of this option if mysqld gives you the
error Too many open files
.
mysqld uses the option value to reserve
descriptors with setrlimit()
. If the
requested number of file descriptors cannot be allocated,
mysqld writes a warning to the error log.
mysqld may attempt to allocate more than
the requested number of descriptors (if they are available),
using the values of
max_connections
and
table_open_cache
to estimate
whether more descriptors will be needed.
Command-Line Format | --partition |
|
Config-File Format | partition |
|
Option Sets Variable | Yes, have_partitioning
|
|
Variable Name | partition |
|
Variable Scope | Global | |
Dynamic Variable | No | |
Disabled by | skip-partition |
|
Permitted Values | ||
Type | boolean |
|
Default | ON |
Enables or disables user-defined partitioning support in the MySQL Server.
Command-Line Format | --pid-file=name |
|
Config-File Format | pid-file |
|
Option Sets Variable | Yes, pid_file
|
|
Variable Name | pid_file |
|
Variable Scope | Global | |
Dynamic Variable | No | |
Permitted Values | ||
Type | filename |
The path name of the process ID file. The server creates the file in the data directory unless an absolute path name is given to specify a different directory. This file is used by other programs such as mysqld_safe to determine the server's process ID.
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 4.2.3.2, “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 unambigously 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.
Command-Line Format | --plugin-load=plugin_list |
|
Config-File Format | plugin-load |
|
Permitted Values | ||
Type | string |
This option tells the server to load the named plugins at
startup. The option value is a semicolon-separated list of
pairs. Each name
=plugin_library
name
is the name of the
plugin, and plugin_library
is the
name of the shared library that contains the plugin code. Each
library file must be located in the directory named by the
plugin_dir
system variable.
For example, if plugins named myplug1
and
myplug2
have library files
myplug1.so
and
myplug2.so
, use this option to load them
at startup:
shell> mysqld --plugin-load=myplug1=myplug1.so;myplug2=myplug2.so
All plugins to load must be named in the same
--plugin-load
option. If
multiple --plugin-load
options
are given, only the last one is used.
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.
Under normal startup, 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, it
does not consult the mysql.plugins
table
and thus does not load plugins installed with the
INSTALL PLUGIN
statement.
--plugin-load
enables plugins
to be loaded even when
--skip-grant-tables
is given.
--plugin-load
also enables
plugins to be loaded at startup under configurations when
plugins cannot be loaded at runtime.
For additional information about plugin loading, see Section 12.4.3.1, “Installing and Uninstalling Plugins”.
--port=
,
port_num
-P
port_num
Command-Line Format | --port=# |
|
Config-File Format | port |
|
Option Sets Variable | Yes, port
|
|
Variable Name | port |
|
Variable Scope | Global | |
Dynamic Variable | No | |
Permitted Values | ||
Type | numeric |
|
Default | 3306 |
The port number to use when listening for TCP/IP connections.
The port number must be 1024 or higher unless the server is
started by the root
system user.
Command-Line Format | --port-open-timeout=# |
|
Config-File Format | port-open-timeout |
|
Permitted Values | ||
Type | numeric |
|
Default | 0 |
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.
Command-Line Format | --safe-mode |
|
Config-File Format | safe-mode |
|
Deprecated | 5.0 |
Skip some optimization stages.
Command-Line Format | --safe-show-database |
|
Config-File Format | safe-show-database |
|
Variable Name | safe_show_database |
|
Variable Scope | Global | |
Dynamic Variable | Yes | |
Deprecated | 4.0.2 | |
Permitted Values | ||
Type | boolean |
This option is deprecated and does not do anything because
there is a SHOW DATABASES
privilege that can be used to control access to database names
on a per-account basis. See
Section 5.4.1, “Privileges Provided by MySQL”.
--safe-show-database
was
removed in MySQL 5.5.3.
Command-Line Format | --safe-user-create |
|
Config-File Format | safe-user-create |
|
Permitted Values | ||
Type | boolean |
|
Default | FALSE |
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
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.
Command-Line Format | --secure-auth |
|
Config-File Format | secure-auth |
|
Option Sets Variable | Yes, secure_auth
|
|
Variable Name | secure_auth |
|
Variable Scope | Global | |
Dynamic Variable | Yes | |
Permitted Values | ||
Type | boolean |
|
Default | FALSE |
Disallow authentication by clients that attempt to use accounts that have old (pre-4.1) passwords.
Command-Line Format | --secure-file-priv |
|
Config-File Format | secure-file-priv |
|
Option Sets Variable | Yes, secure_file_priv
|
|
Variable Name | secure_file_priv |
|
Variable Scope | Global | |
Dynamic Variable | No | |
Permitted Values | ||
Type | string |
This option limits the effect of the
LOAD_FILE()
function and the
LOAD DATA
and
SELECT ... INTO
OUTFILE
statements to work only with files in the
specified directory.
Enable shared-memory connections by local clients. This option is available only on Windows.
--shared-memory-base-name=
name
The name of shared memory to use for shared-memory
connections. This option is available only on Windows. The
default name is MYSQL
. The name is case
sensitive.
Turn off the ability to select and insert at the same time on
MyISAM
tables. (This is to be used only if
you think you have found a bug in this feature.) See
Section 7.3.3, “Concurrent Inserts”.
Do not use external locking (system locking). For more information about external locking, including conditions under which it can and cannot be used, see Section 7.3.5, “External Locking”.
External locking has been disabled by default since MySQL 4.0.
Command-Line Format | --skip-event-scheduler |
|
Config-File Format | skip-event-scheduler |
Turns the Event Scheduler OFF
. This is not
the same as disabling the Event Scheduler, which requires
setting
--event-scheduler=DISABLED
; see
The
--event-scheduler
Option, for more
information.
This option causes the server to start without using the
privilege system at all, which gives anyone with access to the
server unrestricted access to all
databases. You can cause a running server to start
using the grant tables again by executing mysqladmin
flush-privileges or mysqladmin
reload command from a system shell, or by issuing a
MySQL FLUSH
PRIVILEGES
statement after connecting to the server.
This option also suppresses loading of plugins, user-defined
functions (UDFs), and scheduled events. To cause plugins to be
loaded anyway, use the
--plugin-load
option.
--skip-grant-tables
is
unavailable if MySQL was configured with the
--disable-grant-options
option. See Section 2.10.2, “Typical configure Options”.
Do not use the internal host name cache for faster name-to-IP resolution. Instead, query the DNS server every time a client connects. See Section 7.5.11, “How MySQL Uses DNS”.
Disable the InnoDB
storage engine. This
saves memory and disk space and might speed up some
operations. Do not use this option if you require
InnoDB
tables.
Do not resolve host names when checking client connections.
Use only IP numbers. If you use this option, all
Host
column values in the grant tables must
be IP numbers or localhost
. See
Section 7.5.11, “How MySQL Uses DNS”.
Don't listen for TCP/IP connections at all. All interaction with mysqld must be made via named pipes or shared memory (on Windows) or Unix socket files (on Unix). This option is highly recommended for systems where only local clients are allowed. See Section 7.5.11, “How MySQL Uses DNS”.
Command-Line Format | --skip-partition |
|
Config-File Format | skip-partition |
Disables user-defined partitioning. Existing partitioned tables cannot be accessed when the server has been started with this option.
Options that begin with --ssl
specify whether to allow clients to connect via SSL and
indicate where to find SSL keys and certificates. See
Section 5.5.6.3, “SSL Command Options”.
Command-Line Format | --standalone |
|
Config-File Format | standalone |
|
Platform Specific | windows |
Available on Windows NT-based systems only; instructs the MySQL server not to run as a service.
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
Command-Line Format | --symbolic-links |
|
Config-File Format | symbolic-links |
Enable or disable symbolic link support. This option has different effects on Windows and Unix:
On Windows, enabling symbolic links allows you to
establish a symbolic link to a database directory by
creating a
file that contains the path to the real directory. See
Section 7.6.1.3, “Using Symbolic Links for Databases on Windows”.
db_name
.sym
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
options 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 7.6.1.2, “Using Symbolic Links for Tables on Unix”.
Command-Line Format | --skip-safe-malloc |
|
Config-File Format | skip-safemalloc |
If MySQL is configured with
--with-debug=full
, all MySQL
programs check for memory overruns during each memory
allocation and memory freeing operation. This checking is very
slow, so for the server you can avoid it when you don't need
it by using the
--skip-safemalloc
option.
Command-Line Format | --skip-show-database |
|
Config-File Format | skip-show-database |
|
Option Sets Variable | Yes, skip_show_database
|
|
Variable Name | skip_show_database |
|
Variable Scope | Global | |
Dynamic Variable | No |
With this option, the SHOW
DATABASES
statement is allowed only to users who
have the SHOW DATABASES
privilege, and the statement displays all database names.
Without this option, SHOW
DATABASES
is allowed to all users, but displays each
database name only if the user has the
SHOW DATABASES
privilege or
some privilege for the database. Note that
any global privilege is considered a
privilege for the database.
Command-Line Format | --skip-stack-trace |
|
Config-File Format | skip-stack-trace |
Don't 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 MySQL Internals: Porting.
Command-Line Format | --skip-thread-priority |
|
Config-File Format | skip-thread-priority |
|
Deprecated | 5.1.29 |
Disable using thread priorities for faster response time. This option is deprecated.
Command-Line Format | --slow-query-log |
|
Config-File Format | slow-query-log |
|
Option Sets Variable | Yes, slow_query_log
|
|
Variable Name | slow_query_log |
|
Variable Scope | Global | |
Dynamic Variable | Yes | |
Permitted Values | ||
Type | boolean |
|
Default | OFF |
Specify the initial slow query log state. With no argument or
an argument of 1, the
--slow-query-log
option enables
the log. If omitted or given with an argument of 0, the option
disables the log.
Command-Line Format | --socket=name |
|
Config-File Format | socket |
|
Option Sets Variable | Yes, socket
|
|
Variable Name | socket |
|
Variable Scope | Global | |
Dynamic Variable | No | |
Permitted Values | ||
Type | filename |
|
Default | /tmp/mysql.sock |
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
...]]
Command-Line Format | --sql-mode=name |
|
Config-File Format | sql-mode |
|
Option Sets Variable | Yes, sql_mode
|
|
Variable Name | sql_mode |
|
Variable Scope | Both | |
Dynamic Variable | Yes | |
Permitted Values | ||
Type | set |
|
Default | '' |
|
Valid Values |
ALLOW_INVALID_DATES , ANSI_QUOTES , ERROR_FOR_DIVISION_BY_ZERO , HIGH_NOT_PRECEDENCE , IGNORE_SPACE , NO_AUTO_CREATE_USER , NO_AUTO_VALUE_ON_ZERO , NO_BACKSLASH_ESCAPES , NO_DIR_IN_CREATE , NO_ENGINE_SUBSTITUTION , NO_FIELD_OPTIONS , NO_KEY_OPTIONS , NO_TABLE_OPTIONS , NO_UNSIGNED_SUBTRACTION , NO_ZERO_DATE , NO_ZERO_IN_DATE , ONLY_FULL_GROUP_BY , PAD_CHAR_TO_FULL_LENGTH , PIPES_AS_CONCAT , REAL_AS_FLOAT , STRICT_ALL_TABLES , STRICT_TRANS_TABLES
|
Set the SQL mode. See Section 5.1.8, “Server SQL Modes”.
Command-Line Format | --sysdate-is-now |
|
Config-File Format | sysdate-is-now |
|
Permitted Values | ||
Type | boolean |
|
Default | FALSE |
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 an alias for NOW()
. For
information about the implications for binary logging and
replication, see the description for
SYSDATE()
in
Section 11.6, “Date and Time Functions” and for SET
TIMESTAMP
in
Section 5.1.5, “Session System Variables”.
--tc-heuristic-recover={COMMIT|ROLLBACK}
Command-Line Format | --tc-heuristic-recover=name |
|
Config-File Format | tc-heuristic-recover |
|
Permitted Values | ||
Type | enumeration |
|
Valid Values |
COMMIT , RECOVER
|
The type of decision to use in the heuristic recovery process. Currently, this option is unused.
Command-Line Format | --temp-pool |
|
Config-File Format | temp-pool |
|
Permitted Values | ||
Type | boolean |
|
Default | TRUE |
This option 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. This option is ignored except on Linux.
Command-Line Format | --transaction-isolation=name |
|
Config-File Format | transaction-isolation |
|
Permitted Values | ||
Type | enumeration |
|
Valid Values |
READ-UNCOMMITTED , READ-COMMITTED , REPEATABLE-READ , SERIALIZABLE
|
Sets the default transaction isolation level. The
level
value can be
READ-UNCOMMITTED
,
READ-COMMITTED
,
REPEATABLE-READ
, or
SERIALIZABLE
. See
Section 12.3.6, “SET TRANSACTION
Syntax”.
--tmpdir=
,
path
-t
path
Command-Line Format | --tmpdir=name |
|
Config-File Format | tmpdir |
|
Option Sets Variable | Yes, tmpdir
|
|
Variable Name | tmpdir |
|
Variable Scope | Global | |
Dynamic Variable | No | |
Permitted Values | ||
Type | filename |
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, NetWare, and OS/2. If the MySQL server is acting
as a replication slave, you should not set
--tmpdir
to point to a
directory on a memory-based file system or to a directory that
is cleared when the server host restarts. For more information
about the storage location of temporary files, see
Section B.5.4.4, “Where MySQL Stores Temporary Files”. A replication slave needs
some of its temporary files to survive a machine restart so
that it can replicate temporary tables or
LOAD DATA
INFILE
operations. If files in the temporary file
directory are lost when the server restarts, replication
fails.
--user={
,
user_name
|user_id
}-u
{
user_name
|user_id
}
Command-Line Format | --user=name |
|
Config-File Format | user |
|
Permitted Values | ||
Type | string |
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 5.3.1, “General 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.
Use this option with the --help
option for detailed help.
--version
, -V
Display version information and exit.
You can assign a value to a server system variable by using an
option of the form
--
.
For example, var_name
=value
--key_buffer_size=32M
sets the key_buffer_size
variable
to a value of 32MB.
Note that when you assign a value to a variable, MySQL might automatically correct the value to stay within a given range, or adjust the value to the closest allowable value if only certain values are allowed.
If you want to restrict the maximum value to which a variable can
be set at runtime with
SET
, you can
define this by using the
--maximum-
command-line option.
var_name
=value
You can change the values of most system variables for a running
server with the
SET
statement. See Section 12.4.4, “SET
Syntax”.
Section 5.1.4, “Server System Variables”, provides a full description for all variables, and additional information for setting them at server startup and runtime. Section 7.5.3, “Tuning Server Parameters”, includes information on optimizing the server by tuning system variables.
User Comments
open_files_limit: If your mysql server process runs as mysql then the setrlimit will not raise higher then the calling safe_mysqld process. Thus relying on max_connections*5 does not work for a Linux ulimit. Use open_files_limit to go beyond 1024.
To get the server listening on all interfaces, use 0.0.0.0 as the bind address. i.e.:
--bind-address=0.0.0.0
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