4.5.4 mysqldump — A Database Backup Program

• Performance and Scalability Considerations

• Invocation Syntax

• Option Syntax - Alphabetical Summary

The mysqldump client utility performs logical backups, producing a set of SQL statements that can be executed to reproduce the original database object definitions and table data. It dumps one or more MySQL databases for backup or transfer to another SQL server. The mysqldump command can also generate output in CSV, other delimited text, or XML format.

mysqldump requires at least the SELECT privilege for dumped tables, SHOW VIEW for dumped views, TRIGGER for dumped triggers, and LOCK TABLES if the --single-transaction option is not used. Certain options might require other privileges as noted in the option descriptions.

To reload a dump file, you must have the privileges required to execute the statements that it contains, such as the appropriate CREATE privileges for objects created by those statements.

mysqldump output can include ALTER DATABASE statements that change the database collation. These may be used when dumping stored programs to preserve their character encodings. To reload a dump file containing such statements, the ALTER privilege for the affected database is required.

If you are performing a backup on the server and your tables all are MyISAM tables, you can also use mysqlhotcopy for this purpose.

Note

A dump made using PowerShell on Windows with output redirection creates a file that has UTF-16 encoding:

shell> mysqldump [options] > dump.sql

However, UTF-16 is not permitted as a connection character set (see Impermissible Client Character Sets), so the dump file will not load correctly. To work around this issue, use the --result-file option, which creates the output in ASCII format:

shell> mysqldump [options] --result-file=dump.sql

Performance and Scalability Considerations

mysqldump advantages include the convenience and flexibility of viewing or even editing the output before restoring. You can clone databases for development and DBA work, or produce slight variations of an existing database for testing. It is not intended as a fast or scalable solution for backing up substantial amounts of data. With large data sizes, even if the backup step takes a reasonable time, restoring the data can be very slow because replaying the SQL statements involves disk I/O for insertion, index creation, and so on.

For large-scale backup and restore, a physical backup is more appropriate, to copy the data files in their original format that can be restored quickly:

• If your tables are primarily InnoDB tables, or if you have a mix of InnoDB and MyISAM tables, consider using the mysqlbackup command of the MySQL Enterprise Backup product. (Available as part of the Enterprise subscription.) It provides the best performance for InnoDB backups with minimal disruption; it can also back up tables from MyISAM and other storage engines; and it provides a number of convenient options to accommodate different backup scenarios. See Section 25.2, “MySQL Enterprise Backup Overview”.

• If your tables are primarily MyISAM tables, consider using the mysqlhotcopy instead, for better performance than mysqldump of backup and restore operations. See Section 4.6.9, “mysqlhotcopy — A Database Backup Program”.

mysqldump can retrieve and dump table contents row by row, or it can retrieve the entire content from a table and buffer it in memory before dumping it. Buffering in memory can be a problem if you are dumping large tables. To dump tables row by row, use the --quick option (or --opt, which enables --quick). The --opt option (and hence --quick) is enabled by default, so to enable memory buffering, use --skip-quick.

If you are using a recent version of mysqldump to generate a dump to be reloaded into a very old MySQL server, use the --skip-opt option instead of the --opt or --extended-insert option.

For additional information about mysqldump, see Section 7.4, “Using mysqldump for Backups”.

Invocation Syntax

There are in general three ways to use mysqldump—in order to dump a set of one or more tables, a set of one or more complete databases, or an entire MySQL server—as shown here:

shell> mysqldump [options] db_name [tbl_name ...]
shell> mysqldump [options] --databases db_name ...
shell> mysqldump [options] --all-databases

To dump entire databases, do not name any tables following db_name, or use the --databases or --all-databases option.

mysqldump does not dump the INFORMATION_SCHEMA or performance_schema database by default. To dump either of these, name it explicitly on the command line and also use the --skip-lock-tables option. You can also name them with the --databases option. Before MySQL 5.5 mysqldump silently ignores INFORMATION_SCHEMA even if you name it explicitly on the command line.

mysqldump does not dump the performance_schema database.

Before MySQL 5.5.25, mysqldump does not dump the general_log or slow_query_log tables for dumps of the mysql database. As of 5.5.25, the dump includes statements to recreate those tables so that they are not missing after reloading the dump file. Log table contents are not dumped.

mysqldump also does not dump the NDB Cluster ndbinfo information database.

To see a list of the options your version of mysqldump supports, execute mysqldump --help.

Some mysqldump options are shorthand for groups of other options:

• Use of --opt is the same as specifying --add-drop-table, --add-locks, --create-options, --disable-keys, --extended-insert, --lock-tables, --quick, and --set-charset. All of the options that --opt stands for also are on by default because --opt is on by default.

• Use of --compact is the same as specifying --skip-add-drop-table, --skip-add-locks, --skip-comments, --skip-disable-keys, and --skip-set-charset options.

To reverse the effect of a group option, uses its --skip-xxx form (--skip-opt or --skip-compact). It is also possible to select only part of the effect of a group option by following it with options that enable or disable specific features. Here are some examples:

• To select the effect of --opt except for some features, use the --skip option for each feature. To disable extended inserts and memory buffering, use --opt --skip-extended-insert --skip-quick. (Actually, --skip-extended-insert --skip-quick is sufficient because --opt is on by default.)

• To reverse --opt for all features except index disabling and table locking, use --skip-opt --disable-keys --lock-tables.

When you selectively enable or disable the effect of a group option, order is important because options are processed first to last. For example, --disable-keys --lock-tables --skip-opt would not have the intended effect; it is the same as --skip-opt by itself.

mysqldump can retrieve and dump table contents row by row, or it can retrieve the entire content from a table and buffer it in memory before dumping it. Buffering in memory can be a problem if you are dumping large tables. To dump tables row by row, use the --quick option (or --opt, which enables --quick). The --opt option (and hence --quick) is enabled by default, so to enable memory buffering, use --skip-quick.

If you are using a recent version of mysqldump to generate a dump to be reloaded into a very old MySQL server, you should not use the --opt or --extended-insert option. Use --skip-opt instead.

For additional information about mysqldump, see Section 7.4, “Using mysqldump for Backups”.

Option Syntax - Alphabetical Summary

mysqldump supports the following options, which can be specified on the command line or in the [mysqldump] and [client] groups of an option file. For information about option files used by MySQL programs, see Section 4.2.6, “Using Option Files”.

Table 4.11 mysqldump Options

Format	Description	Introduced	Removed
--add-drop-database	Add DROP DATABASE statement before each CREATE DATABASE statement
--add-drop-table	Add DROP TABLE statement before each CREATE TABLE statement
--add-locks	Surround each table dump with LOCK TABLES and UNLOCK TABLES statements
--all-databases	Dump all tables in all databases
--allow-keywords	Allow creation of column names that are keywords
--apply-slave-statements	Include STOP SLAVE prior to CHANGE MASTER statement and START SLAVE at end of output	5.5.3
--bind-address	Use specified network interface to connect to MySQL Server	5.5.8
--character-sets-dir	Directory where character sets are installed
--comments	Add comments to dump file
--compact	Produce more compact output
--compatible	Produce output that is more compatible with other database systems or with older MySQL servers
--complete-insert	Use complete INSERT statements that include column names
--compress	Compress all information sent between client and server
--create-options	Include all MySQL-specific table options in CREATE TABLE statements
--databases	Interpret all name 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	5.5.9
--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
--delayed-insert	Write INSERT DELAYED statements rather than INSERT statements
--delete-master-logs	On a master replication server, delete the binary logs after performing the dump operation
--disable-keys	For each table, surround INSERT statements with statements to disable and enable keys
--dump-date	Include dump date as "Dump completed on" comment if --comments is given
--dump-slave	Include CHANGE MASTER statement that lists binary log coordinates of slave's master	5.5.3
--enable-cleartext-plugin	Enable cleartext authentication plugin	5.5.47
--events	Dump events from dumped databases
--extended-insert	Use multiple-row INSERT syntax
--fields-enclosed-by	This option is used with the --tab option and has the same meaning as the corresponding clause for LOAD DATA INFILE
--fields-escaped-by	This option is used with the --tab option and has the same meaning as the corresponding clause for LOAD DATA INFILE
--fields-optionally-enclosed-by	This option is used with the --tab option and has the same meaning as the corresponding clause for LOAD DATA INFILE
--fields-terminated-by	This option is used with the --tab option and has the same meaning as the corresponding clause for LOAD DATA INFILE
--first-slave	Deprecated; use --lock-all-tables instead		5.5.3
--flush-logs	Flush MySQL server log files before starting dump
--flush-privileges	Emit a FLUSH PRIVILEGES statement after dumping mysql database
--force	Continue even if an SQL error occurs during a table dump
--help	Display help message and exit
--hex-blob	Dump binary columns using hexadecimal notation
--host	Host to connect to (IP address or hostname)
--ignore-table	Do not dump given table
--include-master-host-port	Include MASTER_HOST/MASTER_PORT options in CHANGE MASTER statement produced with --dump-slave	5.5.3
--insert-ignore	Write INSERT IGNORE rather than INSERT statements
--lines-terminated-by	This option is used with the --tab option and has the same meaning as the corresponding clause for LOAD DATA INFILE
--lock-all-tables	Lock all tables across all databases
--lock-tables	Lock all tables before dumping them
--log-error	Append warnings and errors to named file
--master-data	Write the binary log file name and position to the output
--max_allowed_packet	Maximum packet length to send to or receive from server
--net_buffer_length	Buffer size for TCP/IP and socket communication
--no-autocommit	Enclose the INSERT statements for each dumped table within SET autocommit = 0 and COMMIT statements
--no-create-db	Do not write CREATE DATABASE statements
--no-create-info	Do not write CREATE TABLE statements that re-create each dumped table
--no-data	Do not dump table contents
--no-defaults	Read no option files
--no-set-names	Same as --skip-set-charset
--no-tablespaces	Do not write any CREATE LOGFILE GROUP or CREATE TABLESPACE statements in output
--opt	Shorthand for --add-drop-table --add-locks --create-options --disable-keys --extended-insert --lock-tables --quick --set-charset.
--order-by-primary	Dump each table's rows sorted by its primary key, or by its first unique index
--password	Password to use when connecting to server
--pipe	On Windows, connect to server using named pipe
--plugin-dir	Directory where plugins are installed	5.5.9
--port	TCP/IP port number for connection
--print-defaults	Print default options
--protocol	Connection protocol to use
--quick	Retrieve rows for a table from the server a row at a time
--quote-names	Quote identifiers within backtick characters
--replace	Write REPLACE statements rather than INSERT statements
--result-file	Direct output to a given file
--routines	Dump stored routines (procedures and functions) from dumped databases
--set-charset	Add SET NAMES default_character_set to output
--shared-memory-base-name	The name of shared memory to use for shared-memory connections
--single-transaction	Issue a BEGIN SQL statement before dumping data from server
--skip-add-drop-table	Do not add a DROP TABLE statement before each CREATE TABLE statement
--skip-add-locks	Do not add locks
--skip-comments	Do not add comments to dump file
--skip-compact	Do not produce more compact output
--skip-disable-keys	Do not disable keys
--skip-extended-insert	Turn off extended-insert
--skip-opt	Turn off options set by --opt
--skip-quick	Do not retrieve rows for a table from the server a row at a time
--skip-quote-names	Do not quote identifiers
--skip-set-charset	Do not write SET NAMES statement
--skip-triggers	Do not dump triggers
--skip-tz-utc	Turn off tz-utc
--socket	For connections to localhost, the Unix socket file to use
--ssl	Enable encrypted connection
--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	List of permitted ciphers for connection encryption
--ssl-key	File that contains X.509 key
--ssl-mode	Security state of connection to server	5.5.49
--ssl-verify-server-cert	Verify host name against server certificate Common Name identity
--tab	Produce tab-separated data files
--tables	Override --databases or -B option
--triggers	Dump triggers for each dumped table
--tz-utc	Add SET TIME_ZONE='+00:00' to dump file
--user	MySQL user name to use when connecting to server
--verbose	Verbose mode
--version	Display version information and exit
--where	Dump only rows selected by given WHERE condition
--xml	Produce XML output

• --help, -?

  Display a help message and exit.

• --add-drop-database

  Write a DROP DATABASE statement before each CREATE DATABASE statement. This option is typically used in conjunction with the --all-databases or --databases option because no CREATE DATABASE statements are written unless one of those options is specified.

• --add-drop-table

  Write a DROP TABLE statement before each CREATE TABLE statement.

• --add-drop-trigger

  Write a DROP TRIGGER statement before each CREATE TRIGGER statement.

  Note

  This option is supported only by mysqldump as supplied with NDB Cluster. It is not available when using MySQL Server 5.5.

• --add-locks

  Surround each table dump with LOCK TABLES and UNLOCK TABLES statements. This results in faster inserts when the dump file is reloaded. See Section 8.2.4.1, “Optimizing INSERT Statements”.

• --all-databases, -A

  Dump all tables in all databases. This is the same as using the --databases option and naming all the databases on the command line.

• --all-tablespaces, -Y

  Adds to a table dump all SQL statements needed to create any tablespaces used by an NDBCLUSTER table. This information is not otherwise included in the output from mysqldump. This option is currently relevant only to NDB Cluster tables.

• --allow-keywords

  Permit creation of column names that are keywords. This works by prefixing each column name with the table name.

• --apply-slave-statements

  For a slave dump produced with the --dump-slave option, add a STOP SLAVE statement before the CHANGE MASTER TO statement and a START SLAVE statement at the end of the output. This option was added in MySQL 5.5.3.

• --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.

  This option is supported only in the version of mysqldump that is supplied with NDB Cluster. It is not available in standard MySQL Server 5.5 releases.

• --character-sets-dir=dir_name

  The directory where character sets are installed. See Section 10.14, “Character Set Configuration”.

• --comments, -i

  Write additional information in the dump file such as program version, server version, and host. This option is enabled by default. To suppress this additional information, use --skip-comments.

• --compact

  Produce more compact output. This option enables the --skip-add-drop-table, --skip-add-locks, --skip-comments, --skip-disable-keys, and --skip-set-charset options.

• --compatible=name

  Produce output that is more compatible with other database systems or with older MySQL servers. The value of name can be ansi, mysql323, mysql40, postgresql, oracle, mssql, db2, maxdb, no_key_options, no_table_options, or no_field_options. To use several values, separate them by commas. These values have the same meaning as the corresponding options for setting the server SQL mode. See Section 5.1.10, “Server SQL Modes”.

  This option does not guarantee compatibility with other servers. It only enables those SQL mode values that are currently available for making dump output more compatible. For example, --compatible=oracle does not map data types to Oracle types or use Oracle comment syntax.

• --complete-insert, -c

  Use complete INSERT statements that include column names.

• --compress, -C

  Compress all information sent between the client and the server if both support compression.

• --create-options

  Include all MySQL-specific table options in the CREATE TABLE statements.

• --databases, -B

  Dump several databases. Normally, mysqldump treats the first name argument on the command line as a database name and following names as table names. With this option, it treats all name arguments as database names. CREATE DATABASE and USE statements are included in the output before each new database.

  This option may be used to dump the INFORMATION_SCHEMA and performance_schema databases, which normally are not dumped even with the --all-databases option. (Also use the --skip-lock-tables option.)

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

  Write a debugging log. A typical debug_options string is d:t:o,file_name. The default value is d:t:o,/tmp/mysqldump.trace.

• --debug-check

  Print some debugging information when the program exits.

• --debug-info

  Print debugging information and memory and CPU usage statistics when the program exits.

• --default-auth=plugin

  A hint about the client-side authentication plugin to use. See Section 6.3.6, “Pluggable Authentication”.

  This option was added in MySQL 5.5.9.

• --default-character-set=charset_name

  Use charset_name as the default character set. See Section 10.14, “Character Set Configuration”. If no character set is specified, mysqldump uses utf8.

• --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. Before MySQL 5.5.8, file_name must be the full path name to the file. As of MySQL 5.5.8, the name is interpreted relative to the current directory if given as a relative path name.

• --defaults-file=file_name

  Use only the given option file. If the file does not exist or is otherwise inaccessible, an error occurs. Before MySQL 5.5.8, file_name must be the full path name to the file. As of MySQL 5.5.8, the name is interpreted relative to the current directory if given as a relative path name.

• --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, mysqldump normally reads the [client] and [mysqldump] groups. If the --defaults-group-suffix=_other option is given, mysqldump also reads the [client_other] and [mysqldump_other] groups.

• --delayed-insert

  Write INSERT DELAYED statements rather than INSERT statements.

• --delete-master-logs

  On a master replication server, delete the binary logs by sending a PURGE BINARY LOGS statement to the server after performing the dump operation. This option automatically enables --master-data.

• --disable-keys, -K

  For each table, surround the INSERT statements with /*!40000 ALTER TABLE tbl_name DISABLE KEYS */; and /*!40000 ALTER TABLE tbl_name ENABLE KEYS */; statements. This makes loading the dump file faster because the indexes are created after all rows are inserted. This option is effective only for nonunique indexes of MyISAM tables. It has no effect for other tables.

• --dump-date

  If the --comments option is given, mysqldump produces a comment at the end of the dump of the following form:

  -- Dump completed on DATE

  However, the date causes dump files taken at different times to appear to be different, even if the data are otherwise identical. --dump-date and --skip-dump-date control whether the date is added to the comment. The default is --dump-date (include the date in the comment). --skip-dump-date suppresses date printing.

• --dump-slave[=value]

  This option is similar to --master-data except that it is used to dump a replication slave server to produce a dump file that can be used to set up another server as a slave that has the same master as the dumped server. It causes the dump output to include a CHANGE MASTER TO statement that indicates the binary log coordinates (file name and position) of the dumped slave's master. These are the master server coordinates from which the slave should start replicating.

  --dump-slave causes the coordinates from the master to be used rather than those of the dumped server, as is done by the --master-data option. In addition, specfiying this option causes the --master-data option to be overridden, if used, and effectively ignored.

  The option value is handled the same way as for --master-data (setting no value or 1 causes a CHANGE MASTER TO statement to be written to the dump, setting 2 causes the statement to be written but encased in SQL comments) and has the same effect as --master-data in terms of enabling or disabling other options and in how locking is handled.

  This option causes mysqldump to stop the slave SQL thread before the dump and restart it again after.

  In conjunction with --dump-slave, the --apply-slave-statements and --include-master-host-port options can also be used.

  This option was added in MySQL 5.5.3.

• --events, -E

  Include Event Scheduler events for the dumped databases in the output. This option requires the EVENT privileges for those databases.

• --extended-insert, -e

  Write INSERT statements using multiple-row syntax that includes several VALUES lists. This results in a smaller dump file and speeds up inserts when the file is reloaded.

• --fields-terminated-by=..., --fields-enclosed-by=..., --fields-optionally-enclosed-by=..., --fields-escaped-by=...

  These options are used with the --tab option and have the same meaning as the corresponding FIELDS clauses for LOAD DATA INFILE. See Section 13.2.6, “LOAD DATA INFILE Syntax”.

• --first-slave

  Deprecated. Use --lock-all-tables instead. --first-slave was removed in MySQL 5.5.3.

• --flush-logs, -F

  Flush the MySQL server log files before starting the dump. This option requires the RELOAD privilege. If you use this option in combination with the --all-databases option, the logs are flushed for each database dumped. The exception is when using --lock-all-tables, --master-data, or (as of MySQL 5.5.21) --single-transaction: In this case, the logs are flushed only once, corresponding to the moment that all tables are locked by FLUSH TABLES WITH READ LOCK. If you want your dump and the log flush to happen at exactly the same moment, you should use --flush-logs together with --lock-all-tables, --master-data, or --single-transaction.

• --flush-privileges

  Add a FLUSH PRIVILEGES statement to the dump output after dumping the mysql database. This option should be used any time the dump contains the mysql database and any other database that depends on the data in the mysql database for proper restoration.

• --force, -f

  Continue even if an SQL error occurs during a table dump.

  One use for this option is to cause mysqldump to continue executing even when it encounters a view that has become invalid because the definition refers to a table that has been dropped. Without --force, mysqldump exits with an error message. With --force, mysqldump prints the error message, but it also writes an SQL comment containing the view definition to the dump output and continues executing.

• --enable-cleartext-plugin

  Enable the mysql_clear_password cleartext authentication plugin. (See Section 6.5.1.3, “Client-Side Cleartext Pluggable Authentication”.)

  This option was added in MySQL 5.5.47.

• --host=host_name, -h host_name

  Dump data from the MySQL server on the given host. The default host is localhost.

• --hex-blob

  Dump binary columns using hexadecimal notation (for example, 'abc' becomes 0x616263). The affected data types are BINARY, VARBINARY, the BLOB types, and BIT.

• --include-master-host-port

  For the CHANGE MASTER TO statement in a slave dump produced with the --dump-slave option, add MASTER_HOST and MASTER_PORT options for the host name and TCP/IP port number of the slave's master. This option was added in MySQL 5.5.3.

• --ignore-table=db_name.tbl_name

  Do not dump the given table, which must be specified using both the database and table names. To ignore multiple tables, use this option multiple times. This option also can be used to ignore views.

• --insert-ignore

  Write INSERT IGNORE statements rather than INSERT statements.

• --lines-terminated-by=...

  This option is used with the --tab option and has the same meaning as the corresponding LINES clause for LOAD DATA INFILE. See Section 13.2.6, “LOAD DATA INFILE Syntax”.

• --lock-all-tables, -x

  Lock all tables across all databases. This is achieved by acquiring a global read lock for the duration of the whole dump. This option automatically turns off --single-transaction and --lock-tables.

• --lock-tables, -l

  For each dumped database, lock all tables to be dumped before dumping them. The tables are locked with READ LOCAL to permit concurrent inserts in the case of MyISAM tables. For transactional tables such as InnoDB, --single-transaction is a much better option than --lock-tables because it does not need to lock the tables at all.

  Because --lock-tables locks tables for each database separately, this option does not guarantee that the tables in the dump file are logically consistent between databases. Tables in different databases may be dumped in completely different states.

  Some options, such as --opt, automatically enable --lock-tables. If you want to override this, use --skip-lock-tables at the end of the option list.

• --log-error=file_name

  Log warnings and errors by appending them to the named file. The default is to do no logging.

• --master-data[=value]

  Use this option to dump a master replication server to produce a dump file that can be used to set up another server as a slave of the master. It causes the dump output to include a CHANGE MASTER TO statement that indicates the binary log coordinates (file name and position) of the dumped server. These are the master server coordinates from which the slave should start replicating after you load the dump file into the slave.

  If the option value is 2, the CHANGE MASTER TO statement is written as an SQL comment, and thus is informative only; it has no effect when the dump file is reloaded. If the option value is 1, the statement is not written as a comment and takes effect when the dump file is reloaded. If no option value is specified, the default value is 1.

  This option requires the RELOAD privilege and the binary log must be enabled.

  The --master-data option automatically turns off --lock-tables. It also turns on --lock-all-tables, unless --single-transaction also is specified, in which case, a global read lock is acquired only for a short time at the beginning of the dump (see the description for --single-transaction). In all cases, any action on logs happens at the exact moment of the dump.

  It is also possible to set up a slave by dumping an existing slave of the master. In MySQL 5.5.3 and higher, you can create such a dump using the --dump-slave option, which overrides --master-data and causes it to be ignored if both options are used.

  Before MySQL 5.5.3, use the following procedure on the existing slave:

  1. Stop the slave's SQL thread and get its current status:

     mysql> STOP SLAVE SQL_THREAD;
     mysql> SHOW SLAVE STATUS;

  2. From the output of the SHOW SLAVE STATUS statement, the binary log coordinates of the master server from which the new slave should start replicating are the values of the Relay_Master_Log_File and Exec_Master_Log_Pos fields. Denote those values as file_name and file_pos.

  3. Dump the slave server:

     shell> mysqldump --master-data=2 --all-databases > dumpfile

     Using --master-data=2 works only if binary logging has been enabled on the slave. Otherwise, mysqldump fails with the error Binlogging on server not active. In this case you must handle any locking issues in another manner, using one or more of --add-locks, --lock-tables, --lock-all-tables, or --single-transaction, as required by your application and environment.

  4. Restart the slave:

     mysql> START SLAVE;

  5. On the new slave, load the dump file:

     shell> mysql < dumpfile

  6. On the new slave, set the replication coordinates to those of the master server obtained earlier:

     mysql> CHANGE MASTER TO
         -> MASTER_LOG_FILE = 'file_name', MASTER_LOG_POS = file_pos;

     The CHANGE MASTER TO statement might also need other parameters, such as MASTER_HOST to point the slave to the correct master server host. Add any such parameters as necessary.

• --no-autocommit

  Enclose the INSERT statements for each dumped table within SET autocommit = 0 and COMMIT statements.

• --no-create-db, -n

  Suppress the CREATE DATABASE statements that are otherwise included in the output if the --databases or --all-databases option is given.

• --no-create-info, -t

  Do not write CREATE TABLE statements that create each dumped table.

  Note

  This option does not exclude statements creating log file groups or tablespaces from mysqldump output; however, you can use the --no-tablespaces option for this purpose.

• --no-data, -d

  Do not write any table row information (that is, do not dump table contents). This is useful if you want to dump only the CREATE TABLE statement for the table (for example, to create an empty copy of the table by loading the dump file).

• --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.

• --no-set-names, -N

  This has the same effect as --skip-set-charset.

• --no-tablespaces, -y

  This option suppresses all CREATE LOGFILE GROUP and CREATE TABLESPACE statements in the output of mysqldump.

• --opt

  This option is shorthand. It is the same as specifying --add-drop-table --add-locks --create-options --disable-keys --extended-insert --lock-tables --quick --set-charset. It should give you a fast dump operation and produce a dump file that can be reloaded into a MySQL server quickly.

  The --opt option is enabled by default. Use --skip-opt to disable it. See the discussion at the beginning of this section for information about selectively enabling or disabling a subset of the options affected by --opt.

• --order-by-primary

  Dump each table's rows sorted by its primary key, or by its first unique index, if such an index exists. This is useful when dumping a MyISAM table to be loaded into an InnoDB table, but will make the dump operation take considerably longer.

• --password[=password], -p[password]

  The password to use when connecting to the server. If you use the short option form (-p), you cannot have a space between the option and the password. If you omit the password value following the --password or -p option on the command line, mysqldump prompts for one.

  Specifying a password on the command line should be considered insecure. See Section 6.1.2.1, “End-User Guidelines for Password Security”. You can use an option file to avoid giving the password on the command line.

• --pipe, -W

  On Windows, connect to the server using a named pipe. This option applies only if the server supports named-pipe connections.

• --plugin-dir=dir_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 mysqldump does not find it. See Section 6.3.6, “Pluggable Authentication”.

  This option was added in MySQL 5.5.9.

• --port=port_num, -P port_num

  The TCP/IP port number to use for the connection.

• --print-defaults

  Print the program name and all options that it gets from option files.

• --protocol={TCP|SOCKET|PIPE|MEMORY}

  The connection protocol to use for connecting to the server. It is useful when the other connection parameters normally would cause a protocol to be used other than the one you want. For details on the permissible values, see Section 4.2.2, “Connecting to the MySQL Server”.

• --quick, -q

  This option is useful for dumping large tables. It forces mysqldump to retrieve rows for a table from the server a row at a time rather than retrieving the entire row set and buffering it in memory before writing it out.

• --quote-names, -Q

  Quote identifiers (such as database, table, and column names) within ` characters. If the ANSI_QUOTES SQL mode is enabled, identifiers are quoted within " characters. This option is enabled by default. It can be disabled with --skip-quote-names, but this option should be given after any option such as --compatible that may enable --quote-names.

• --replace

  Write REPLACE statements rather than INSERT statements.

• --result-file=file_name, -r file_name

  Direct output to the named file. The result file is created and its previous contents overwritten, even if an error occurs while generating the dump.

  This option should be used on Windows to prevent newline \n characters from being converted to \r\n carriage return/newline sequences.

• --routines, -R

  Include stored routines (procedures and functions) for the dumped databases in the output. This option requires the SELECT privilege for the mysql.proc table.

  The output generated by using --routines contains CREATE PROCEDURE and CREATE FUNCTION statements to create the routines. However, these statements do not include attributes such as the routine creation and modification timestamps, so when the routines are reloaded, they are created with timestamps equal to the reload time.

  If you require routines to be created with their original timestamp attributes, do not use --routines. Instead, dump and reload the contents of the mysql.proc table directly, using a MySQL account that has appropriate privileges for the mysql database.

  Prior to MySQL 5.5.21, this option had no effect when used together with the --xml option. (Bug #11760384, Bug #52792)

• --set-charset

  Write SET NAMES default_character_set to the output. This option is enabled by default. To suppress the SET NAMES statement, use --skip-set-charset.

• --shared-memory-base-name=name

  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.

  The server must be started with the --shared-memory option to enable shared-memory connections.

• --single-transaction

  This option sets the transaction isolation mode to REPEATABLE READ and sends a START TRANSACTION SQL statement to the server before dumping data. It is useful only with transactional tables such as InnoDB, because then it dumps the consistent state of the database at the time when START TRANSACTION was issued without blocking any applications.

  When using this option, you should keep in mind that only InnoDB tables are dumped in a consistent state. For example, any MyISAM or MEMORY tables dumped while using this option may still change state.

  While a --single-transaction dump is in process, to ensure a valid dump file (correct table contents and binary log coordinates), no other connection should use the following statements: ALTER TABLE, CREATE TABLE, DROP TABLE, RENAME TABLE, TRUNCATE TABLE. A consistent read is not isolated from those statements, so use of them on a table to be dumped can cause the SELECT that is performed by mysqldump to retrieve the table contents to obtain incorrect contents or fail.

  The --single-transaction option and the --lock-tables option are mutually exclusive because LOCK TABLES causes any pending transactions to be committed implicitly.

  This option is not supported for NDB Cluster tables; the results cannot be guaranteed to be consistent due to the fact that the NDBCLUSTER storage engine supports only the READ_COMMITTED transaction isolation level. You should always use NDB backup and restore instead.

  To dump large tables, combine the --single-transaction option with the --quick option.

• --skip-comments

  See the description for the --comments option.

• --skip-opt

  See the description for the --opt option.

• --socket=path, -S path

  For connections to localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.

• --ssl*

  Options that begin with --ssl specify whether to connect to the server using SSL and indicate where to find SSL keys and certificates. See Section 6.4.2, “Command Options for Encrypted Connections”.

• --tab=dir_name, -T dir_name

  Produce tab-separated text-format data files. For each dumped table, mysqldump creates a tbl_name.sql file that contains the CREATE TABLE statement that creates the table, and the server writes a tbl_name.txt file that contains its data. The option value is the directory in which to write the files.

  Note

  This option should be used only when mysqldump is run on the same machine as the mysqld server. Because the server creates *.txt files in the directory that you specify, the directory must be writable by the server and the MySQL account that you use must have the FILE privilege. Because mysqldump creates *.sql in the same directory, it must be writable by your system login account.

  By default, the .txt data files are formatted using tab characters between column values and a newline at the end of each line. The format can be specified explicitly using the --fields-xxx and --lines-terminated-by options.

  Column values are converted to the character set specified by the --default-character-set option.

• --tables

  Override the --databases or -B option. mysqldump regards all name arguments following the option as table names.

• --triggers

  Include triggers for each dumped table in the output. This option is enabled by default; disable it with --skip-triggers.

  To be able to dump a table's triggers, you must have the TRIGGER privilege for the table.

• --tz-utc

  This option enables TIMESTAMP columns to be dumped and reloaded between servers in different time zones. mysqldump sets its connection time zone to UTC and adds SET TIME_ZONE='+00:00' to the dump file. Without this option, TIMESTAMP columns are dumped and reloaded in the time zones local to the source and destination servers, which can cause the values to change if the servers are in different time zones. --tz-utc also protects against changes due to daylight saving time. --tz-utc is enabled by default. To disable it, use --skip-tz-utc.

• --user=user_name, -u user_name

  The MySQL user name to use when connecting to the server.

• --verbose, -v

  Verbose mode. Print more information about what the program does.

• --version, -V

  Display version information and exit.

• --where='where_condition', -w 'where_condition'

  Dump only rows selected by the given WHERE condition. Quotes around the condition are mandatory if it contains spaces or other characters that are special to your command interpreter.

  Examples:

  --where="user='jimf'"
  -w"userid>1"
  -w"userid<1"

• --xml, -X

  Write dump output as well-formed XML.

  NULL, 'NULL', and Empty Values: For a column named column_name, the NULL value, an empty string, and the string value 'NULL' are distinguished from one another in the output generated by this option as follows.

  Value:	XML Representation:
  NULL (unknown value)	<field name="column_name" xsi:nil="true" />
  '' (empty string)	<field name="column_name"></field>
  'NULL' (string value)	<field name="column_name">NULL</field>

  The output from the mysql client when run using the --xml option also follows the preceding rules. (See Section 4.5.1.1, “mysql Options”.)

  XML output from mysqldump includes the XML namespace, as shown here:

  shell> mysqldump --xml -u root world City
  <?xml version="1.0"?>
  <mysqldump xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <database name="world">
  <table_structure name="City">
  <field Field="ID" Type="int(11)" Null="NO" Key="PRI" Extra="auto_increment" />
  <field Field="Name" Type="char(35)" Null="NO" Key="" Default="" Extra="" />
  <field Field="CountryCode" Type="char(3)" Null="NO" Key="" Default="" Extra="" />
  <field Field="District" Type="char(20)" Null="NO" Key="" Default="" Extra="" />
  <field Field="Population" Type="int(11)" Null="NO" Key="" Default="0" Extra="" />
  <key Table="City" Non_unique="0" Key_name="PRIMARY" Seq_in_index="1" Column_name="ID"
  Collation="A" Cardinality="4079" Null="" Index_type="BTREE" Comment="" />
  <options Name="City" Engine="MyISAM" Version="10" Row_format="Fixed" Rows="4079"
  Avg_row_length="67" Data_length="273293" Max_data_length="18858823439613951"
  Index_length="43008" Data_free="0" Auto_increment="4080"
  Create_time="2007-03-31 01:47:01" Update_time="2007-03-31 01:47:02"
  Collation="latin1_swedish_ci" Create_options="" Comment="" />
  </table_structure>
  <table_data name="City">
  <row>
  <field name="ID">1</field>
  <field name="Name">Kabul</field>
  <field name="CountryCode">AFG</field>
  <field name="District">Kabol</field>
  <field name="Population">1780000</field>
  </row>
  
  ...
  
  <row>
  <field name="ID">4079</field>
  <field name="Name">Rafah</field>
  <field name="CountryCode">PSE</field>
  <field name="District">Rafah</field>
  <field name="Population">92020</field>
  </row>
  </table_data>
  </database>
  </mysqldump>

  Prior to MySQL 5.5.21, this option prevented the --routines option from working correctly—that is, no stored routines, triggers, or events could be dumped in XML format. (Bug #11760384, Bug #52792)

You can also set the following variables by using --var_name=value syntax:

• max_allowed_packet

  The maximum size of the buffer for client/server communication. The default is 24MB, the maximum is 1GB.

• net_buffer_length

  The initial size of the buffer for client/server communication. When creating multiple-row INSERT statements (as with the --extended-insert or --opt option), mysqldump creates rows up to net_buffer_length bytes long. If you increase this variable, ensure that the MySQL server net_buffer_length system variable has a value at least this large.

A common use of mysqldump is for making a backup of an entire database:

shell> mysqldump db_name > backup-file.sql

You can load the dump file back into the server like this:

shell> mysql db_name < backup-file.sql

Or like this:

shell> mysql -e "source /path-to-backup/backup-file.sql" db_name

mysqldump is also very useful for populating databases by copying data from one MySQL server to another:

shell> mysqldump --opt db_name | mysql --host=remote_host -C db_name

It is possible to dump several databases with one command:

shell> mysqldump --databases db_name1 [db_name2 ...] > my_databases.sql

To dump all databases, use the --all-databases option:

shell> mysqldump --all-databases > all_databases.sql

For InnoDB tables, mysqldump provides a way of making an online backup:

shell> mysqldump --all-databases --master-data --single-transaction > all_databases.sql

This backup acquires a global read lock on all tables (using FLUSH TABLES WITH READ LOCK) at the beginning of the dump. As soon as this lock has been acquired, the binary log coordinates are read and the lock is released. If long updating statements are running when the FLUSH statement is issued, the MySQL server may get stalled until those statements finish. After that, the dump becomes lock free and does not disturb reads and writes on the tables. If the update statements that the MySQL server receives are short (in terms of execution time), the initial lock period should not be noticeable, even with many updates.

For point-in-time recovery (also known as “roll-forward,” when you need to restore an old backup and replay the changes that happened since that backup), it is often useful to rotate the binary log (see Section 5.4.4, “The Binary Log”) or at least know the binary log coordinates to which the dump corresponds:

shell> mysqldump --all-databases --master-data=2 > all_databases.sql

Or:

shell> mysqldump --all-databases --flush-logs --master-data=2
              > all_databases.sql

The --master-data and --single-transaction options can be used simultaneously, which provides a convenient way to make an online backup suitable for use prior to point-in-time recovery if tables are stored using the InnoDB storage engine.

For more information on making backups, see Section 7.2, “Database Backup Methods”, and Section 7.3, “Example Backup and Recovery Strategy”.

If you encounter problems backing up views, please read the section that covers restrictions on views which describes a workaround for backing up views when this fails due to insufficient privileges. See Section C.5, “Restrictions on Views”.