6.5.3 mysqldump — 数据库备份程序
The mysqlcheck client performs table maintenance: It checks, repairs, optimizes, or analyzes tables.
Each table is locked and therefore unavailable to other sessions while it is being processed, although for check operations, the table is locked with a READ
lock only (see Section 15.3.6, “LOCK TABLES and UNLOCK TABLES Statements”, for more information about READ
and WRITE
locks). Table maintenance operations can be time-consuming, particularly for large tables. If you use the --databases
or --all-databases
option to process all tables in one or more databases, an invocation of mysqlcheck might take a long time. (This is also true for the MySQL upgrade procedure if it determines that table checking is needed because it processes tables the same way.)
mysqlcheck must be used when the mysqld server is running, which means that you do not have to stop the server to perform table maintenance.
mysqlcheck uses the SQL statements CHECK TABLE
, REPAIR TABLE
, ANALYZE TABLE
, and OPTIMIZE TABLE
in a convenient way for the user. It determines which statements to use for the operation you want to perform, and then sends the statements to the server to be executed. For details about which storage engines each statement works with, see the descriptions for those statements in Section 15.7.3, “Table Maintenance Statements”.
All storage engines do not necessarily support all four maintenance operations. In such cases, an error message is displayed. For example, if test.t
is an MEMORY
table, an attempt to check it produces this result:
$> mysqlcheck test t
test.t
note : The storage engine for the table doesn't support check
If mysqlcheck is unable to repair a table, see Section 3.14, “Rebuilding or Repairing Tables or Indexes” for manual table repair strategies. This is the case, for example, for InnoDB
tables, which can be checked with CHECK TABLE
, but not repaired with REPAIR TABLE
.
It is best to make a backup of a table before performing a table repair operation; under some circumstances the operation might cause data loss. Possible causes include but are not limited to file system errors.
There are three general ways to invoke mysqlcheck:
mysqlcheck [options] db_name [tbl_name ...]
mysqlcheck [options] --databases db_name ...
mysqlcheck [options] --all-databases
If you do not name any tables following db_name
or if you use the --databases
or --all-databases
option, entire databases are checked.
mysqlcheck has a special feature compared to other client programs. The default behavior of checking tables (--check
) can be changed by renaming the binary. If you want to have a tool that repairs tables by default, you should just make a copy of mysqlcheck named mysqlrepair, or make a symbolic link to mysqlcheck named mysqlrepair. If you invoke mysqlrepair, it repairs tables.
The names shown in the following table can be used to change mysqlcheck default behavior.
Command | Meaning |
---|---|
mysqlrepair | The default option is --repair |
mysqlanalyze | The default option is --analyze |
mysqloptimize | The default option is --optimize |
mysqlcheck supports the following options, which can be specified on the command line or in the [mysqlcheck]
and [client]
groups of an option file. For information about option files used by MySQL programs, see Section 6.2.2.2, “Using Option Files”.
Table 6.12 mysqlcheck Options
Option Name | Description |
---|---|
--all-databases | Check all tables in all databases |
--all-in-1 | Execute a single statement for each database that names all the tables from that database |
--analyze | Analyze the tables |
--auto-repair | If a checked table is corrupted, automatically fix it |
--bind-address | Use specified network interface to connect to MySQL Server |
--character-sets-dir | Directory where character sets are installed |
--check | Check the tables for errors |
--check-only-changed | Check only tables that have changed since the last check |
--check-upgrade | Invoke CHECK TABLE with the FOR UPGRADE option |
--compress | Compress all information sent between client and server |
--compression-algorithms | Permitted compression algorithms for connections to server |
--databases | Interpret all arguments as database names |
--debug | Write debugging log |
--debug-check | Print debugging information when program exits |
--debug-info | Print debugging information, memory, and CPU statistics when program exits |
--default-auth | Authentication plugin to use |
--default-character-set | Specify default character set |
--defaults-extra-file | Read named option file in addition to usual option files |
--defaults-file | Read only named option file |
--defaults-group-suffix | Option group suffix value |
--enable-cleartext-plugin | Enable cleartext authentication plugin |
--extended | Check and repair tables |
--fast | Check only tables that have not been closed properly |
--force | Continue even if an SQL error occurs |
--get-server-public-key | Request RSA public key from server |
--help | Display help message and exit |
--host | Host on which MySQL server is located |
--login-path | Read login path options from .mylogin.cnf |
--medium-check | Do a check that is faster than an --extended operation |
--no-defaults | Read no option files |
--no-login-paths | Do not read login paths from the login path file |
--optimize | Optimize the tables |
--password | Password to use when connecting to server |
--password1 | First multifactor authentication password to use when connecting to server |
--password2 | Second multifactor authentication password to use when connecting to server |
--password3 | Third multifactor authentication password to use when connecting to server |
--pipe | Connect to server using named pipe (Windows only) |
--plugin-dir | Directory where plugins are installed |
--port | TCP/IP port number for connection |
--print-defaults | Print default options |
--protocol | Transport protocol to use |
--quick | The fastest method of checking |
--repair | Perform a repair that can fix almost anything except unique keys that are not unique |
--server-public-key-path | Path name to file containing RSA public key |
--shared-memory-base-name | Shared-memory name for shared-memory connections (Windows only) |
--silent | Silent mode |
--skip-database | Omit this database from performed operations |
--socket | Unix socket file or Windows named pipe to use |
--ssl-ca | File that contains list of trusted SSL Certificate Authorities |
--ssl-capath | Directory that contains trusted SSL Certificate Authority certificate files |
--ssl-cert | File that contains X.509 certificate |
--ssl-cipher | Permissible ciphers for connection encryption |
--ssl-crl | File that contains certificate revocation lists |
--ssl-crlpath | Directory that contains certificate revocation-list files |
--ssl-fips-mode | Whether to enable FIPS mode on client side |
--ssl-key | File that contains X.509 key |
--ssl-mode | Desired security state of connection to server |
--ssl-session-data | File that contains SSL session data |
--ssl-session-data-continue-on-failed-reuse | Whether to establish connections if session reuse fails |
--tables | Overrides the --databases or -B option |
--tls-ciphersuites | Permissible TLSv1.3 ciphersuites for encrypted connections |
--tls-sni-servername | Server name supplied by the client |
--tls-version | Permissible TLS protocols for encrypted connections |
--use-frm | For repair operations on MyISAM tables |
--user | MySQL user name to use when connecting to server |
--verbose | Verbose mode |
--version | Display version information and exit |
--write-binlog | Log ANALYZE, OPTIMIZE, REPAIR statements to binary log. --skip-write-binlog adds NO_WRITE_TO_BINLOG to these statements |
--zstd-compression-level | Compression level for connections to server that use zstd compression |
-
--help
,-?
Command-Line Format --help
Display a help message and exit.
-
--all-databases
,-A
Command-Line Format --all-databases
Check all tables in all databases. This is the same as using the
--databases
option and naming all the databases on the command line, except that theINFORMATION_SCHEMA
andperformance_schema
databases are not checked. They can be checked by explicitly naming them with the--databases
option. -
--all-in-1
,-1
Command-Line Format --all-in-1
Instead of issuing a statement for each table, execute a single statement for each database that names all the tables from that database to be processed.
-
--analyze
,-a
Command-Line Format --analyze
Analyze the tables.
-
Command-Line Format --auto-repair
If a checked table is corrupted, automatically fix it. Any necessary repairs are done after all tables have been checked.
-
Command-Line Format --bind-address=ip_address
On a computer having multiple network interfaces, use this option to select which interface to use for connecting to the MySQL server.
-
Command-Line Format --character-sets-dir=dir_name
Type Directory name The directory where character sets are installed. See Section 12.15, “Character Set Configuration”.
-
--check
,-c
Command-Line Format --check
Check the tables for errors. This is the default operation.
-
Command-Line Format --check-only-changed
Check only tables that have changed since the last check or that have not been closed properly.
-
--check-upgrade
,-g
Command-Line Format --check-upgrade
Invoke
CHECK TABLE
with theFOR UPGRADE
option to check tables for incompatibilities with the current version of the server. -
Command-Line Format --compress[={OFF|ON}]
Deprecated Yes Type Boolean Default Value OFF
Compress all information sent between the client and the server if possible. See Section 6.2.8, “Connection Compression Control”.
This option is deprecated. Expect it to be removed in a future version of MySQL. See Configuring Legacy Connection Compression.
-
--compression-algorithms=
value
Command-Line Format --compression-algorithms=value
Type Set Default Value uncompressed
Valid Values zlib
zstd
uncompressed
The permitted compression algorithms for connections to the server. The available algorithms are the same as for the
protocol_compression_algorithms
system variable. The default value isuncompressed
.For more information, see Section 6.2.8, “Connection Compression Control”.
-
--databases
,-B
Command-Line Format --databases
Process all tables in the named databases. Normally, mysqlcheck treats the first name argument on the command line as a database name and any following names as table names. With this option, it treats all name arguments as database names.
-
--debug[=
,debug_options
]-# [
debug_options
]Command-Line Format --debug[=debug_options]
Type String Default Value d:t:o
Write a debugging log. A typical
debug_options
string isd:t:o,
. The default isfile_name
d:t:o
.This option is available only if MySQL was built using
WITH_DEBUG
. MySQL release binaries provided by Oracle are not built using this option. -
Command-Line Format --debug-check
Type Boolean Default Value FALSE
Print some debugging information when the program exits.
This option is available only if MySQL was built using
WITH_DEBUG
. MySQL release binaries provided by Oracle are not built using this option. -
Command-Line Format --debug-info
Type Boolean Default Value FALSE
Print debugging information and memory and CPU usage statistics when the program exits.
This option is available only if MySQL was built using
WITH_DEBUG
. MySQL release binaries provided by Oracle are not built using this option. -
--default-character-set=
charset_name
Command-Line Format --default-character-set=charset_name
Type String Use
charset_name
as the default character set. See Section 12.15, “Character Set Configuration”. -
--defaults-extra-file=
file_name
Command-Line Format --defaults-extra-file=file_name
Type 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.For additional information about this and other option-file options, see Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling”.
-
Command-Line Format --defaults-file=file_name
Type File name Use 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.Exception: Even with
--defaults-file
, client programs read.mylogin.cnf
.For additional information about this and other option-file options, see Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling”.
-
Command-Line Format --defaults-group-suffix=str
Type String Read not only the usual option groups, but also groups with the usual names and a suffix of
str
. For example, mysqlcheck normally reads the[client]
and[mysqlcheck]
groups. If this option is given as--defaults-group-suffix=_other
, mysqlcheck also reads the[client_other]
and[mysqlcheck_other]
groups.For additional information about this and other option-file options, see Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling”.
-
--extended
,-e
Command-Line Format --extended
If you are using this option to check tables, it ensures that they are 100% consistent but takes a long time.
If you are using this option to repair tables, it runs an extended repair that may not only take a long time to execute, but may produce a lot of garbage rows also!
-
Command-Line Format --default-auth=plugin
Type String A hint about which client-side authentication plugin to use. See Section 8.2.17, “Pluggable Authentication”.
-
Command-Line Format --enable-cleartext-plugin
Type Boolean Default Value FALSE
Enable the
mysql_clear_password
cleartext authentication plugin. (See Section 8.4.1.4, “Client-Side Cleartext Pluggable Authentication”.) -
--fast
,-F
Command-Line Format --fast
Check only tables that have not been closed properly.
-
--force
,-f
Command-Line Format --force
Continue even if an SQL error occurs.
-
Command-Line Format --get-server-public-key
Type Boolean Request from the server the public key required for RSA key pair-based password exchange. This option applies to clients that authenticate with the
caching_sha2_password
authentication plugin. For that plugin, the server does not send the public key unless requested. This option is ignored for accounts that do not authenticate with that plugin. It is also ignored if RSA-based password exchange is not used, as is the case when the client connects to the server using a secure connection.If
--server-public-key-path=
is given and specifies a valid public key file, it takes precedence overfile_name
--get-server-public-key
.For information about the
caching_sha2_password
plugin, see Section 8.4.1.2, “Caching SHA-2 Pluggable Authentication”. -
--host=
,host_name
-h
host_name
Command-Line Format --host=host_name
Type String Default Value localhost
Connect to the MySQL server on the given host.
-
Command-Line Format --login-path=name
Type String Read options from the named login path in the
.mylogin.cnf
login path file. A “login path” is an option group containing options that specify which MySQL server to connect to and which account to authenticate as. To create or modify a login path file, use the mysql_config_editor utility. See Section 6.6.7, “mysql_config_editor — MySQL Configuration Utility”.For additional information about this and other option-file options, see Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling”.
-
Command-Line Format --no-login-paths
Skips reading options from the login path file.
See
--login-path
for related information.For additional information about this and other option-file options, see Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling”.
-
--medium-check
,-m
Command-Line Format --medium-check
Do a check that is faster than an
--extended
operation. This finds only 99.99% of all errors, which should be good enough in most cases. -
Command-Line Format --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.The exception is that the
.mylogin.cnf
file is read in all cases, if it exists. This permits passwords to be specified in a safer way than on the command line even when--no-defaults
is used. To create.mylogin.cnf
, use the mysql_config_editor utility. See Section 6.6.7, “mysql_config_editor — MySQL Configuration Utility”.For additional information about this and other option-file options, see Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling”.
-
--optimize
,-o
Command-Line Format --optimize
Optimize the tables.
-
--password[=
,password
]-p[
password
]Command-Line Format --password[=password]
Type String The password of the MySQL account used for connecting to the server. The password value is optional. If not given, mysqlcheck prompts for one. If given, there must be no space between
--password=
or-p
and the password following it. If no password option is specified, the default is to send no password.Specifying a password on the command line should be considered insecure. To avoid giving the password on the command line, use an option file. See Section 8.1.2.1, “End-User Guidelines for Password Security”.
To explicitly specify that there is no password and that mysqlcheck should not prompt for one, use the
--skip-password
option. -
The password for multifactor authentication factor 1 of the MySQL account used for connecting to the server. The password value is optional. If not given, mysqlcheck prompts for one. If given, there must be no space between
--password1=
and the password following it. If no password option is specified, the default is to send no password.Specifying a password on the command line should be considered insecure. To avoid giving the password on the command line, use an option file. See Section 8.1.2.1, “End-User Guidelines for Password Security”.
To explicitly specify that there is no password and that mysqlcheck should not prompt for one, use the
--skip-password1
option.--password1
and--password
are synonymous, as are--skip-password1
and--skip-password
. -
The password for multifactor authentication factor 2 of the MySQL account used for connecting to the server. The semantics of this option are similar to the semantics for
--password1
; see the description of that option for details. -
The password for multifactor authentication factor 3 of the MySQL account used for connecting to the server. The semantics of this option are similar to the semantics for
--password1
; see the description of that option for details. -
--pipe
,-W
Command-Line Format --pipe
Type String On Windows, connect to the server using a named pipe. This option applies only if the server was started with the
named_pipe
system variable enabled to support named-pipe connections. In addition, the user making the connection must be a member of the Windows group specified by thenamed_pipe_full_access_group
system variable. -
Command-Line Format --plugin-dir=dir_name
Type Directory name The directory in which to look for plugins. Specify this option if the
--default-auth
option is used to specify an authentication plugin but mysqlcheck does not find it. See Section 8.2.17, “Pluggable Authentication”. -
--port=
,port_num
-P
port_num
Command-Line Format --port=port_num
Type Numeric Default Value 3306
For TCP/IP connections, the port number to use.
-
Command-Line Format --print-defaults
Print the program name and all options that it gets from option files.
For additional information about this and other option-file options, see Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling”.
-
--protocol={TCP|SOCKET|PIPE|MEMORY}
Command-Line Format --protocol=type
Type String Default Value [see text]
Valid Values TCP
SOCKET
PIPE
MEMORY
The transport protocol to use for connecting to the server. It is useful when the other connection parameters normally result in use of a protocol other than the one you want. For details on the permissible values, see Section 6.2.7, “Connection Transport Protocols”.
-
--quick
,-q
Command-Line Format --quick
If you are using this option to check tables, it prevents the check from scanning the rows to check for incorrect links. This is the fastest check method.
If you are using this option to repair tables, it tries to repair only the index tree. This is the fastest repair method.
-
--repair
,-r
Command-Line Format --repair
Perform a repair that can fix almost anything except unique keys that are not unique.
-
--server-public-key-path=
file_name
Command-Line Format --server-public-key-path=file_name
Type File name The path name to a file in PEM format containing a client-side copy of the public key required by the server for RSA key pair-based password exchange. This option applies to clients that authenticate with the
sha256_password
orcaching_sha2_password
authentication plugin. This option is ignored for accounts that do not authenticate with one of those plugins. It is also ignored if RSA-based password exchange is not used, as is the case when the client connects to the server using a secure connection.If
--server-public-key-path=
is given and specifies a valid public key file, it takes precedence overfile_name
--get-server-public-key
.For
sha256_password
, this option applies only if MySQL was built using OpenSSL.For information about the
sha256_password
andcaching_sha2_password
plugins, see Section 8.4.1.3, “SHA-256 Pluggable Authentication”, and Section 8.4.1.2, “Caching SHA-2 Pluggable Authentication”. -
--shared-memory-base-name=
name
Command-Line Format --shared-memory-base-name=name
Platform Specific Windows On Windows, the shared-memory name to use for connections made using shared memory to a local server. The default value is
MYSQL
. The shared-memory name is case-sensitive.This option applies only if the server was started with the
shared_memory
system variable enabled to support shared-memory connections. -
--silent
,-s
Command-Line Format --silent
Silent mode. Print only error messages.
-
Command-Line Format --skip-database=db_name
Do not include the named database (case-sensitive) in the operations performed by mysqlcheck.
-
--socket=
,path
-S
path
Command-Line Format --socket={file_name|pipe_name}
Type String For connections to
localhost
, the Unix socket file to use, or, on Windows, the name of the named pipe to use.On Windows, this option applies only if the server was started with the
named_pipe
system variable enabled to support named-pipe connections. In addition, the user making the connection must be a member of the Windows group specified by thenamed_pipe_full_access_group
system variable. -
Options that begin with
--ssl
specify whether to connect to the server using encryption and indicate where to find SSL keys and certificates. See Command Options for Encrypted Connections. -
--ssl-fips-mode={OFF|ON|STRICT}
Command-Line Format --ssl-fips-mode={OFF|ON|STRICT}
Deprecated Yes Type Enumeration Default Value OFF
Valid Values OFF
ON
STRICT
Controls whether to enable FIPS mode on the client side. The
--ssl-fips-mode
option differs from other--ssl-
options in that it is not used to establish encrypted connections, but rather to affect which cryptographic operations to permit. See Section 8.8, “FIPS Support”.xxx
These
--ssl-fips-mode
values are permitted:-
OFF
: Disable FIPS mode. -
ON
: Enable FIPS mode. -
STRICT
: Enable “strict” FIPS mode.
NoteIf the OpenSSL FIPS Object Module is not available, the only permitted value for
--ssl-fips-mode
isOFF
. In this case, setting--ssl-fips-mode
toON
orSTRICT
causes the client to produce a warning at startup and to operate in non-FIPS mode.This option is deprecated. Expect it to be removed in a future version of MySQL.
-
-
Command-Line Format --tables
Override the
--databases
or-B
option. All name arguments following the option are regarded as table names. -
--tls-ciphersuites=
ciphersuite_list
Command-Line Format --tls-ciphersuites=ciphersuite_list
Type String The permissible ciphersuites for encrypted connections that use TLSv1.3. The value is a list of one or more colon-separated ciphersuite names. The ciphersuites that can be named for this option depend on the SSL library used to compile MySQL. For details, see Section 8.3.2, “Encrypted Connection TLS Protocols and Ciphers”.
-
--tls-sni-servername=
server_name
Command-Line Format --tls-sni-servername=server_name
Type String When specified, the name is passed to the
libmysqlclient
C API library using theMYSQL_OPT_TLS_SNI_SERVERNAME
option ofmysql_options()
. The server name is not case-sensitive. To show which server name the client specified for the current session, if any, check theTls_sni_server_name
status variable.Server Name Indication (SNI) is an extension to the TLS protocol (OpenSSL must be compiled using TLS extensions for this option to function). The MySQL implementation of SNI represents the client-side only.
-
Command-Line Format --tls-version=protocol_list
Type String Default Value TLSv1,TLSv1.1,TLSv1.2,TLSv1.3
(OpenSSL 1.1.1 or higher)TLSv1,TLSv1.1,TLSv1.2
(otherwise)The permissible TLS protocols for encrypted connections. The value is a list of one or more comma-separated protocol names. The protocols that can be named for this option depend on the SSL library used to compile MySQL. For details, see Section 8.3.2, “Encrypted Connection TLS Protocols and Ciphers”.
-
Command-Line Format --use-frm
For repair operations on
MyISAM
tables, get the table structure from the data dictionary so that the table can be repaired even if the.MYI
header is corrupted. -
--user=
,user_name
-u
user_name
Command-Line Format --user=user_name,
Type String The user name of the MySQL account to use for connecting to the server.
-
--verbose
,-v
Command-Line Format --verbose
Verbose mode. Print information about the various stages of program operation.
-
--version
,-V
Command-Line Format --version
Display version information and exit.
-
Command-Line Format --write-binlog
This option is enabled by default, so that
ANALYZE TABLE
,OPTIMIZE TABLE
, andREPAIR TABLE
statements generated by mysqlcheck are written to the binary log. Use--skip-write-binlog
to causeNO_WRITE_TO_BINLOG
to be added to the statements so that they are not logged. Use the--skip-write-binlog
when these statements should not be sent to replicas or run when using the binary logs for recovery from backup. -
--zstd-compression-level=
level
Command-Line Format --zstd-compression-level=#
Type Integer The compression level to use for connections to the server that use the
zstd
compression algorithm. The permitted levels are from 1 to 22, with larger values indicating increasing levels of compression. The defaultzstd
compression level is 3. The compression level setting has no effect on connections that do not usezstd
compression.For more information, see Section 6.2.8, “Connection Compression Control”.