mysqldump — A Database Backup Program

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.

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 4.6.10, “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.

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.

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

Option Syntax 

DDL Options

Usage scenarios for mysqldump include setting up an entire new MySQL instance (including database tables), and replacing data inside an existing instance with existing databases and tables. The following options let you specify which things to tear down and set up when restoring a dump, by encoding various DDL statements within the dump file.

• --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 MySQL 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. 

Replication Options

The mysqldump command is frequently used to create an empty instance, or an instance including data, on a slave server in a replication configuration. The following options apply to dumping and restoring data on replication master and slave servers.

• --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, “Replication Relay and Status Logs”). 
• --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.

Format Options

The following options specify how to represent the entire dump file or certain kinds of data in the dump file. They also control whether certain optional information is written to the dump file.

• --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 5.1.7, “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.
  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, “LOAD DATA INFILE Syntax”. 
• --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, “LOAD DATA INFILE Syntax”. 
• --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 files *.txt file 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 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 5.6.5, 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) 

Filtering Options

The following options control which kinds of schema objects are written to the dump file: by category, such as triggers or events; by name, for example, choosing which databases and tables to dump; or even filtering rows from the table data using a WHERE clause.

• --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, “Replication Relay and Status Logs”) 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. 
• --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. Use of 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: 

Performance Options

The following options are the most relevant for the performance particularly of the restore operations. For large data sets, restore operation (processing the INSERT statements in the dump file) is the most time-consuming part. When it is urgent to restore data quickly, plan and test the performance of this stage in advance. For restore times measured in hours, you might prefer an alternative backup and restore solution, such as MySQL Enterprise Backup for InnoDB-only and mixed-use databases, or mysqlhotcopy for MyISAM-only databases.

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. 

Transactional Options

The following options trade off the performance of the dump operation, against the reliability and consistency of the exported data.

• --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 8.2.2.1, “Speed of INSERT Statements”. 
• --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. 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. 

Option Groups

• 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

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 “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”.

• 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. 

Restrictions

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. You can also name it with the --databases option. Also, use the --skip-lock-tables option.

mysqldump does not dump the MySQL 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, “Restrictions on Views” for a workaround.