mysqldump
MYSQLDUMP(1) MySQL Database System MYSQLDUMP(1)
NAME
mysqldump - a database backup program
SYNOPSIS
mysqldump [options] [db_name [tbl_name ...]]
DESCRIPTION
The mysqldump client is a backup program originally written by Igor
Romanenko. It can be used to dump a database or a collection of
databases for backup or transfer to another SQL server (not necessarily
a MySQL server). The dump typically contains SQL statements to create
the table, populate it, or both. However, mysqldump can also be used to
generate files in CSV, other delimited text, or XML format.
If you are doing a backup on the server and your tables all are MyISAM
tables, consider using the mysqlhotcopy instead because it can
accomplish faster backups and faster restores. See mysqlhotcopy(1).
There are three general ways to invoke mysqldump:
shell> mysqldump [options] db_name [tables]
shell> mysqldump [options] --databases db_name1 [db_name2 db_name3...]
shell> mysqldump [options] --all-databases
If you do not name any tables following db_name or if you use the
--databases or --all-databases option, entire databases are dumped.
To get a list of the options your version of mysqldump supports,
execute mysqldump --help.
Some mysqldump options are shorthand for groups of other options.
--opt and --compact fall into this category. For example, use of --opt
is the same as specifying --add-drop-table --add-locks --create-options
--disable-keys --extended-insert --lock-tables --quick --set-charset.
Note that as of MySQL 4.1, all of the options that --opt stands for
also are on by default because --opt is on by default.
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:
o To select the effect of --opt except for some features, use the
--skip option for each feature. For example, to disable extended
inserts and memory buffering, use --opt --skip-extended-insert
--skip-quick. (As of MySQL 4.1, --skip-extended-insert --skip-quick
is sufficient because --opt is on by default.)
o To reverse --opt for all features except index disabling and table
locking, use --skip-opt --disable-keys --lock-tables.
When you selectively enable or disable the effect of a group option,
order is important because options are processed first to last. For
example, --disable-keys --lock-tables --skip-opt would not have the
intended effect; it is the same as --skip-opt by itself.
mysqldump can retrieve and dump table contents row by row, or it can
retrieve the entire content from a table and buffer it in memory before
dumping it. Buffering in memory can be a problem if you are dumping
large tables. To dump tables row by row, use the --quick option (or
--opt, which enables --quick). --opt (and hence --quick) is enabled by
default as of MySQL 4.1 to enable memory buffering, use --skip-quick.
If you are using a recent version of mysqldump to generate a dump to be
reloaded into a very old MySQL server, you should not use the --opt or
--extended-insert option. Use --skip-opt instead.
Before MySQL 4.1.2, out-of-range numeric values such as -inf and inf,
as well as NaN (not-a-number) values are dumped by mysqldump as NULL.
You can see this using the following sample table:
mysql> CREATE TABLE t (f DOUBLE);
mysql> INSERT INTO t VALUES(1e+111111111111111111111);
mysql> INSERT INTO t VALUES(-1e111111111111111111111);
mysql> SELECT f FROM t;
+------+
| f |
+------+
| inf |
| -inf |
+------+
For this table, mysqldump produces the following data output:
--
-- Dumping data for table `t`
--
INSERT INTO t VALUES (NULL);
INSERT INTO t VALUES (NULL);
The significance of this behavior is that if you dump and restore the
table, the new table has contents that differ from the original
contents. This problem is fixed as of MySQL 4.1.2; you cannot insert
inf in the table, so this mysqldump behavior is only relevant when you
deal with old servers.
mysqldump supports the following options:
o --help, -?
Display a help message and exit.
o --add-drop-database
Add a DROP DATABASE statement before each CREATE DATABASE statement.
Added in MySQL 4.1.13.
o --add-drop-table
Add a DROP TABLE statement before each CREATE TABLE statement.
o --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 2.13, "Speed of INSERT Statements".
o --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.
o --allow-keywords
Allow creation of column names that are keywords. This works by
prefixing each column name with the table name.
o --character-sets-dir=path
The directory where character sets are installed. See Section 9.1,
"The Character Set Used for Data and Sorting".
o --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. This option was added in MySQL 4.0.17.
o --compact
Produce less verbose output. This option suppresses comments and
enables the --skip-add-drop-table, --no-set-names,
--skip-disable-keys, and --skip-add-locks options. Added in MySQL
4.1.2.
o --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 the section called "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.
o --complete-insert, -c
Use complete INSERT statements that include column names.
o --compress, -C
Compress all information sent between the client and the server if
both support compression.
o --create-options
Include all MySQL-specific table options in the CREATE TABLE
statements. Before MySQL 4.1.2, use --all instead.
o --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.
o --debug[=debug_options], -# [debug_options]
Write a debugging log. The debug_options string is often
'd:t:o,file_name'. The default value is
'd:t:o,/tmp/mysqldump.trace'.
o --default-character-set=charset_name
Use charset_name as the default character set. See Section 9.1, "The
Character Set Used for Data and Sorting". If no character set is
specified, mysqldump from MySQL 4.1.2 or later uses utf8, and
earlier versions use latin1.
o --delayed-insert
Write INSERT DELAYED statements rather than INSERT statements.
o --delete-master-logs
On a master replication server, delete the binary logs after
performing the dump operation. This option automatically enables
--first-slave before MySQL 4.1.8 and enables --master-data
thereafter. It was added in MySQL 3.23.57 (for MySQL 3.23) and MySQL
4.0.13 (for MySQL 4.0).
o --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 into a
MySQL 4.0 or newer server faster because the indexes are created
after all rows are inserted. This option is effective for MyISAM
tables only.
o --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.
o --fields-terminated-by=..., --fields-enclosed-by=...,
--fields-optionally-enclosed-by=..., --fields-escaped-by=...
These options are used with the -T option and have the same meaning
as the corresponding clauses for LOAD DATA INFILE. See Section 2.5,
"LOAD DATA INFILE Syntax".
o --first-slave, -x
Deprecated. Renamed to --lock-all-tables in MySQL 4.1.8.
o --flush-logs, -F
Flush the MySQL server log files before starting the dump. This
option requires the RELOAD privilege. Note that if you use this
option in combination with the --all-databases (or -A) option, the
logs are flushed for each database dumped. The exception is when
using --lock-all-tables or --master-data: 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 either
--lock-all-tables or --master-data.
o --force, -f
Continue even if an SQL error occurs during a table dump.
o --host=host_name, -h host_name
Dump data from the MySQL server on the given host. The default host
is localhost.
o --hex-blob
Dump binary columns using hexadecimal notation (for example, 'abc'
becomes 0x616263). The affected data types are BINARY, VARBINARY,
and BLOB in MySQL 4.1 and up, and CHAR BINARY, VARCHAR BINARY, and
BLOB in MySQL 4.0. This option was added in MySQL 4.0.23 and 4.1.8.
o --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 was added in MySQL 4.1.9.
o --insert-ignore
Write INSERT statements with the IGNORE option. This option was
added in MySQL 4.1.12.
o --lines-terminated-by=...
This option is used with the -T option and has the same meaning as
the corresponding clause for LOAD DATA INFILE. See Section 2.5,
"LOAD DATA INFILE Syntax".
o --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.
Added in MySQL 4.1.8.
o --lock-tables, -l
Lock all tables before dumping them. The tables are locked with READ
LOCAL to allow concurrent inserts in the case of MyISAM tables. For
transactional tables such as InnoDB and BDB, --single-transaction is
a much better option, because it does not need to lock the tables at
all.
Please note that when dumping multiple databases, --lock-tables
locks tables for each database separately. Therefore, 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.
o --master-data[=value]
Write the binary log filename and position to the output. This
option requires the RELOAD privilege and the binary log must be
enabled. If the option value is equal to 1, the position and
filename are written to the dump output in the form of a CHANGE
MASTER statement. If the dump is from a master server and you use it
to set up a slave server, the CHANGE MASTER statement causes the
slave to start from the correct position in the master's binary
logs. If the option value is equal to 2, the CHANGE MASTER statement
is written as an SQL comment. (This is the default action if value
is omitted.) value may be given as of MySQL 4.1.8; before that, do
not specify an option value.
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 also the description
for --single-transaction. In all cases, any action on logs happens
at the exact moment of the dump.
o --no-autocommit
Enclose the INSERT statements for each dumped table within SET
AUTOCOMMIT=0 and COMMIT statements.
o --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.
o --no-create-info, -t
Do not write CREATE TABLE statements that re-create each dumped
table.
o --no-data, -d
Do not write any table row information (that is, do not dump table
contents). This is very useful if you want to dump only the CREATE
TABLE statement for the table.
o --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.
As of MySQL 4.1, --opt 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 certain of the
options affected by --opt.
o --order-by-primary
Sorts each table's rows 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
itself take considerably longer. This option was added in MySQL
4.1.8.
o --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, you are prompted for
one.
Specifying a password on the command line should be considered
insecure. See Section 7.6, "Keeping Your Password Secure".
o --port=port_num, -P port_num
The TCP/IP port number to use for the connection.
o --protocol={TCP|SOCKET|PIPE|MEMORY}
The connection protocol to use. Added in MySQL 4.1.
o --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.
o --quote-names, -Q
Quote database, table, and column names within '`' characters. If
the ANSI_QUOTES SQL mode is enabled, names are quoted within '"'
characters. As of MySQL 4.1.1, --quote-names 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.
o --result-file=file, -r file
Direct output to a given file. This option should be used on Windows
to prevent newline '0(cq characters from being converted to '\r0(cq
carriage return/newline sequences. The result file is created and
its contents overwritten, even if an error occurs while generating
the dump. The previous contents are lost.
o --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. This option was added in MySQL 4.1.2.
o --single-transaction
This option issues a BEGIN SQL statement before dumping data from
the server. It is useful only with transactional tables such as
InnoDB and BDB, because then it dumps the consistent state of the
database at the time when BEGIN 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.
The --single-transaction option was added in MySQL 4.0.2. This
option is mutually exclusive with the --lock-tables option, 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, you should combine this option with --quick.
o --skip-opt
See the description for the --opt option.
o --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.
o --skip-comments
See the description for the --comments option.
o --ssl*
Options that begin with --ssl specify whether to connect to the
server via SSL and indicate where to find SSL keys and certificates.
See Section 7.7.3, "SSL Command Options".
o --tab=path, -T path
Produce tab-separated data files. For each dumped table, mysqldump
creates a tbl_name.sql file that contains the CREATE TABLE statement
that creates the table, and a tbl_name.txt file that contains its
data. The option value is the directory in which to write the files.
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--xxx options.
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.
o --tables
Override the --databases or -B option. mysqldump regards all name
arguments following the option as table names.
o --user=user_name, -u user_name
The MySQL username to use when connecting to the server.
o --verbose, -v
Verbose mode. Print more information about what the program does.
o --version, -V
Display version information and exit.
o --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"
o --xml, -X
Write dump output as well-formed XML.
You can also set the following variables by using --var_name=value
syntax:
o max_allowed_packet
The maximum size of the buffer for client/server communication. The
value of the variable can be up to 16MB before MySQL 4.0, and up to
1GB from MySQL 4.0 on.
o net_buffer_length
The initial size of the buffer for client/server communication. When
creating multiple-row-insert statements (as with option
--extended-insert or --opt), 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.
It is also possible to set variables by using
--set-variable=var_name=value or -O var_name=value syntax. However,
this syntax is deprecated as of MySQL 4.0.
The most common use of mysqldump is probably for making a backup of an
entire database:
shell> mysqldump db_name > backup-file.sql
You can read 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 just needs to acquire 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 and only if one long updating
statement is running when the FLUSH statement is issued, the MySQL
server may get stalled until that long statement finishes, and then the
dump becomes lock-free. 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 10.4, "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 as of MySQL 4.1.8, which provides a convenient way to
make an online backup suitable for point-in-time recovery if tables are
stored using the InnoDB storage engine.
For more information on making backups, see Section 8.1, "Database
Backups", and Section 8.2, "Example Backup and Recovery Strategy".
COPYRIGHT
Copyright 1997-2006 MySQL AB
This documentation is NOT distributed under a GPL license. Use of this
documentation is subject to the following terms: You may create a
printed copy of this documentation solely for your own personal use.
Conversion to other formats is allowed as long as the actual content is
not altered or edited in any way. You shall not publish or distribute
this documentation in any form or on any media, except if you
distribute the documentation in a manner similar to how MySQL
disseminates it (that is, electronically for download on a Web site
with the software) or on a CD-ROM or similar medium, provided however
that the documentation is disseminated together with the software on
the same medium. Any other use, such as any dissemination of printed
copies or use of this documentation, in whole or in part, in another
publication, requires the prior written consent from an authorized
representative of MySQL AB. MySQL AB reserves any and all rights to
this documentation not expressly granted above.
Please email <docs@mysql.com> for more information.
SEE ALSO
isamchk(1), isamlog(1), msql2mysql(1), myisam_ftdump(1), myisamchk(1),
myisamlog(1), myisampack(1), mysql(1), mysql.server(1),
mysql_config(1), mysql_explain_log(1), mysql_fix_privilege_tables(1),
mysql_zap(1), mysqlaccess(1), mysqladmin(1), mysqlbinlog(1),
mysqlcheck(1), mysqld(1), mysqld(8), mysqld_multi(1), mysqld_safe(1),
mysqlhotcopy(1), mysqlimport(1), mysqlshow(1), pack_isam(1), perror(1),
replace(1), safe_mysqld(1)
For more information, please refer to the MySQL Reference Manual, which
may already be installed locally and which is also available online at
http://dev.mysql.com/doc/.
AUTHOR
MySQL AB (http://www.mysql.com/). This software comes with no
warranty.
MySQL 4.1 11/02/2006 MYSQLDUMP(1)
