Ubuntu Manpage: mysqldump - a database backup program

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Provided by: percona-xtradb-cluster-client-5.5_5.5.37-25.10+dfsg-0ubuntu0.14.04.5_amd64

NAME

       mysqldump - a database backup program

SYNOPSIS

       mysqldump [options] [db_name [tbl_name ...]]

DESCRIPTION

The mysqldump client is a utility that performs logical backups, producing a set of SQL statements that
can be run to reproduce the original schema objects, table data, or both. It dumps one or more MySQL
database 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 same privileges needed to create each of the dumped objects by
issuing CREATE statements manually.

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.
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 24.2, “MySQL
Enterprise Backup”.

• 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, “Using mysqldump for Backups”.
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 database by default. mysqldump dumps INFORMATION_SCHEMA
only if you name it explicitly on the command line, although currently you must also use the
--skip-lock-tables 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 MySQL 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.

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”.

mysqldump supports the following options, which can be specified on the command line or in the
[mysqldump] and [client] groups of an option file. mysqldump also supports the options for processing
option files described at Section 4.2.3.4, “Command-Line Options that Affect Option-File Handling”.

• --help, -?

Display a help message and exit.

• --add-drop-database

Add 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

Add a DROP TABLE statement before each CREATE TABLE statement.

• --add-drop-trigger

Add a DROP TRIGGER statement before each CREATE TRIGGER statement.

Note
This option is supported only by mysqldump as supplied with MySQL 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 8.2.2.1, “Speed of 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 MySQL 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, this option can be used to select which interface
is employed when connecting to the MySQL server.

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

• --character-sets-dir=path

The directory where character sets are installed. See Section 10.5, “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 5.1.7, “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.

• --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.

• --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

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 10.5, “Character Set Configuration”. If no
character set is specified, mysqldump uses utf8, and earlier versions use latin1.

• --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.

• --extended-insert, -e

Use multiple-row INSERT syntax that include 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. 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.

• --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.

• --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
later, 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.

In MySQL 5.2.2 and earlier, 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

This option suppresses 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 re-create each dumped table.

Note
This option does not 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-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=path

The directory in which to look for plugins. It may be necessary to 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.

• --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 a given file. This option should be used on Windows to prevent newline “\n”
characters from being converted to “\r\n” carriage return/newline sequences. The result file is
created and its previous contents overwritten, even if an error occurs while generating the dump.

• --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 re-create the routines.
However, these statements do not include attributes such as the routine creation and modification
timestamps. This means that when the routines are reloaded, they will be created with the timestamps
equal to the reload time.

If you require routines to be re-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

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

• --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 MySQL 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 6.3.9.4, “SSL Command Options”.

• --tab=path, -T path

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.
You must have the FILE privilege, and the server must have permission to write files in the
directory that you specify.
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.

• --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 the section called “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 length. If you increase this variable, you should also ensure that the
net_buffer_length variable in the MySQL server is at least this large.

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.

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 --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 5.2.4, “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 E.5, “Restrictions on Views”.

COPYRIGHT

       Copyright © 1997, 2014, Oracle and/or its affiliates. All rights reserved.

       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.

       You should have received a copy of the GNU General Public License along with the program; if not, write
       to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA or see
       http://www.gnu.org/licenses/.

AUTHOR

       Oracle Corporation (http://dev.mysql.com/).

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