* Performance and Scalability Considerations

* Invocation Syntax

* Option Syntax - Alphabetical Summary

* Connection Options

* Option-File Options

* DDL Options

* Debug Options

* Help Options

* Internationalization Options

* Replication Options

* Format Options

* Filtering Options

* Performance Options

* Transactional Options

* Option Groups

* Examples

* Restrictions

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.

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 Section 10.1.4, lqConnection Character Sets and Collationsrq), 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

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, lqMySQL Enterprise Backup Overviewrq.

* If your tables are primarily MyISAM tables, consider using the mysqlhotcopy instead, for better performance than mysqldump of backup and restore operations. See mysqlhotcopy(1).

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, lqUsing mysqldump for Backupsrq. Invocation Syntax.PP 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.

To see a list of the options your version of mysqldump supports, issue the command mysqldump --help. Option Syntax - Alphabetical Summary.PP 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, lqUsing Option Filesrq. Connection Options.PP The mysqldump command logs into a MySQL server to extract information. The following options specify how to connect to the MySQL server, either on the same machine or a remote system.

* --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 beginning with MySQL 5.6.1.

* --compress, -C

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

* --default-auth=plugin

A hint about the client-side authentication plugin to use. See Section 6.3.7, lqPluggable Authenticationrq.

* --enable-cleartext-plugin

Enable the mysql_clear_password cleartext authentication plugin. (See Section 6.5.1.5, lqClient-Side Cleartext Pluggable Authenticationrq.)

This option was added in MySQL 5.6.28.

* --host=host_name, -h host_name

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

* --login-path=name

Read options from the named login path in the .mylogin.cnf login path file. A lqlogin pathrq 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 mysql_config_editor(1). This option was added in MySQL 5.6.6.

* --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, lqEnd-User Guidelines for Password Securityrq. 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 6.3.7, lqPluggable Authenticationrq.

* --port=port_num, -P port_num

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

* --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, lqConnecting to the MySQL Serverrq.

* --secure-auth

Do not send passwords to the server in old (pre-4.1) format. This prevents connections except for servers that use the newer password format. This option is enabled by default; use --skip-secure-auth to disable it. This option was added in MySQL 5.6.17.

Note
Passwords that use the pre-4.1 hashing method are less secure than passwords that use the native password hashing method and should be avoided. Pre-4.1 passwords are deprecated and support for them will be removed in a future MySQL release. For account upgrade instructions, see Section 6.5.1.3, lqMigrating Away from Pre-4.1 Password Hashing and the mysql_old_password Pluginrq.

Note
This option is deprecated and will be removed in a future release. As of MySQL 5.7.5, it is always enabled and attempting to disable it produces an error.

* --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 6.4.5, lqCommand Options for Secure Connectionsrq.

* --user=user_name, -u user_name

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

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.

* --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. file_name is interpreted relative to the current directory if given as a relative path name rather than a full 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. file_name is interpreted relative to the current directory if given as a relative path name rather than a full path name.

Exception: Even with --defaults-file, client programs read .mylogin.cnf.

* --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.

* --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, if it exists, is read in all cases. This permits passwords to be specified in a safer way than on the command line even when --no-defaults is used. (.mylogin.cnf is created by the mysql_config_editor utility. See mysql_config_editor(1).)

* --print-defaults

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

* --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.

* --all-tablespaces, -Y

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

* --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-tablespaces, -y

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

* --replace

Write REPLACE statements rather than INSERT statements.

* --allow-keywords

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

* --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.

* --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.

* --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.

* --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.

* --log-error=file_name

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

* --skip-comments

See the description for the --comments option.

* --verbose, -v

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

* --help, -?

Display a help message and exit.

* --version, -V

Display version information and exit.

* --character-sets-dir=dir_name

The directory where character sets are installed. See Section 10.5, lqCharacter Set Configurationrq.

* --default-character-set=charset_name

Use charset_name as the default character set. See Section 10.5, lqCharacter Set Configurationrq. If no character set is specified, mysqldump uses utf8.

* --no-set-names, -N

Turns off the --set-charset setting, the same as specifying --skip-set-charset.

* --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.

* --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.

* --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.

* --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.

* --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.

* --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, using the --dump-slave option, which overrides --master-data and causes it to be ignored if both options are used.

Prior to MySQL 5.6.4, this option was required for dumping the replication log tables (see Section 17.2.2, lqReplication Relay and Status Logsrq).

* --set-gtid-purged=value

This option enables control over global transaction ID (GTID) information written to the dump file, by indicating whether to add a SET @@global.gtid_purged statement to the output. This option may also cause a statement to be written to the output that disables binary logging while the dump file is being reloaded.

The following table shows the permitted option values. The default value is AUTO.

Value	Meaning
OFF	Add no SET statement to the output.
ON	Add a SET statement to the output. An error occurs if                     GTIDs are not enabled on the server.
AUTO	Add a SET statement to the output if GTIDs are                     enabled on the server.

The --set-gtid-purged option has the following effect on binary logging when the dump file is reloaded:

* --set-gtid-purged=OFF: SET @@SESSION.SQL_LOG_BIN=0; is not added to the output.

* --set-gtid-purged=ON: SET @@SESSION.SQL_LOG_BIN=0; is added to the output.

* --set-gtid-purged=AUTO: SET @@SESSION.SQL_LOG_BIN=0; is added to the output if GTIDs are enabled on the server you are backing up (that is, if AUTO evaluates to ON).

This option was added in MySQL 5.6.9.

* --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 5.1.8, lqServer SQL Modesrq.

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.

This option requires a server version of 4.1.0 or higher. With older servers, it does nothing.

* --complete-insert, -c

Use complete INSERT statements that include column names.

* --create-options

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

* --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, lqLOAD DATA INFILE Syntaxrq.

* --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.

* --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, lqLOAD DATA INFILE Syntaxrq.

* --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.

* --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.

* --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.

* --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.

* --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 the section called lqMYSQL OPTIONSrq.)

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 5.6.5, 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)

* --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.

Prior to MySQL 5.6.4, the slave_master_info and slave_relay_log_info tables (see Section 17.2.2, lqReplication Relay and Status Logsrq) were not included by this option.

* --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 performace_schema databases, which normally are not dumped even with the --all-databases option. (Also use the --skip-lock-tables option.)

* --events, -E

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

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

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

* --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.

* --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).

* --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 5.6.5, this option had no effect when used together with the --xml option. (Bug #11760384, Bug #52792)

* --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.

* --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"

Performance is also affected by the transactional options, primarily for the dump operation.

* --delayed-insert

For those nontransactional tables that support the INSERT DELAYED syntax, use that statement rather than regular INSERT statements.

As of MySQL 5.6.6, DELAYED inserts are deprecated, so this option will be removed in a future release.

* --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.

* --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.

* --insert-ignore

Write INSERT IGNORE statements rather than INSERT statements.

* --opt

This option, enabled by default, is shorthand for the combination of --add-drop-table --add-locks --create-options --disable-keys --extended-insert --lock-tables --quick --set-charset. It gives a fast dump operation and produces a dump file that can be reloaded into a MySQL server quickly.

Because the --opt option is enabled by default, you only specify its converse, the --skip-opt to turn off several default settings. See the discussion of mysqldump option groups for information about selectively enabling or disabling a subset of the options affected by --opt.

* --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.

* --skip-opt

See the description for the --opt option.

* --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, lqOptimizing INSERT Statementsrq.

* --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 --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.

* --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.

* --no-autocommit

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

* --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 makes the dump operation take considerably longer.

* --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.

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

* The --opt option turns on several settings that work together to perform a fast dump operation. All of these settings are on by default, because --opt is on by default. Thus you rarely if ever specify --opt. Instead, you can turn these settings off as a group by specifying --skip-opt, the optionally re-enable certain settings by specifying the associated options later on the command line.

* The --compact option turns off several settings that control whether optional statements and comments appear in the output. Again, you can follow this option with other options that re-enable certain settings, or turn all the settings on by using the --skip-compact form.

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. Examples.PP To make a backup of an entire database:

shell> mysqldump db_name > backup-file.sql

To load the dump file back into the server:

shell> mysql db_name < backup-file.sql

Another way to reload the dump file:

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

You can 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 lqroll-forward,rq 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, lqThe Binary Logrq) 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, lqDatabase Backup Methodsrq, and Section 7.3, lqExample Backup and Recovery Strategyrq.

* 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.

mysqldump does not dump the NDB Cluster ndbinfo information database.

Before MySQL 5.6.6, mysqldump does not dump the general_log or slow_query_log tables for dumps of the mysql database. As of 5.6.6, 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.

If you encounter problems backing up views due to insufficient privileges, see Section C.5, lqRestrictions on Viewsrq for a workaround.  

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This documentation is free software; you can redistribute it and/or modify it only under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License.

This documentation is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

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