программа резервного копирования базы данных (a database backup program)
Описание (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 MariaDB 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 four general ways to invoke mysqldump:
shell> mysqldump [options] db_name [tbl_name ...]
shell> mysqldump [options] --databases db_name ...
shell> mysqldump [options] --all-databases
shell> mysqldump [options] --system={options}
If you do not name any tables following db_name or if you use the
--databases or --all-databases option, entire databases are
dumped.
mysqldump does not dump the INFORMATION_SCHEMA or
performance_schema databases by default. To dump these, name them
explicitly on the command line, although you must also use the
--skip-lock-tables option.
To see a list of the options your version of mysqldump supports,
execute mysqldump --help.
Some mysqldump options are shorthand for groups of other options:
• Use of --opt is the same as specifying --add-drop-table,
--add-locks, --create-options, --disable-keys,
--extended-insert, --lock-tables, --quick, and --set-charset.
All of the options that --opt stands for also are on by
default because --opt is on by default.
• Use of --compact is the same as specifying
--skip-add-drop-table, --skip-add-locks, --skip-comments,
--skip-disable-keys, and --skip-set-charset options.
To reverse the effect of a group option, uses its --skip-xxx form
(--skip-opt or --skip-compact). It is also possible to select
only part of the effect of a group option by following it with
options that enable or disable specific features. Here are some
examples:
• To select the effect of --opt except for some features, use
the --skip option for each feature. To disable extended
inserts and memory buffering, use --opt
--skip-extended-insert --skip-quick. (Actually,
--skip-extended-insert --skip-quick is sufficient because
--opt is on by default.)
• To reverse --opt for all features except index disabling and
table locking, use --skip-opt --disable-keys --lock-tables.
When you selectively enable or disable the effect of a group
option, order is important because options are processed first to
last. For example, --disable-keys --lock-tables --skip-opt would
not have the intended effect; it is the same as --skip-opt by
itself.
mysqldump can retrieve and dump table contents row by row, or it
can retrieve the entire content from a table and buffer it in
memory before dumping it. Buffering in memory can be a problem if
you are dumping large tables. To dump tables row by row, use the
--quick option (or --opt, which enables --quick). The --opt
option (and hence --quick) is enabled by default, so to enable
memory buffering, use --skip-quick.
If you are using a recent version of mysqldump to generate a dump
to be reloaded into a very old MySQL server, you should not use
the --opt or --extended-insert option. Use --skip-opt instead.
mysqldump supports the following options, which can be specified
on the command line or in the [mysqldump] and [client] option
file groups. mysqldump also supports the options for processing
option file.
• --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.
• --add-locks
Surround each table dump with LOCK TABLES and UNLOCK TABLES
statements. This results in faster inserts when the dump file
is reloaded.
• --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
Allow creation of column names that are keywords. This works
by prefixing each column name with the table name.
• --apply-slave-statements
Adds 'STOP SLAVE' prior to 'CHANGE MASTER' and 'START SLAVE'
to bottom of dump.
• --character-sets-dir=path
The directory where character sets are installed.
• --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.
This option does not guarantee compatibility with other
servers. It only enables those SQL mode values that are
currently available for making dump output more compatible.
For example, --compatible=oracle does not map data types to
Oracle types or use Oracle comment syntax.
• --complete-insert, -c
Use complete INSERT statements that include column names.
• --compress, -C
Compress all information sent between the client and the
server if both support compression.
• --copy-s3-tables
By default S3 tables are ignored. With this option set, the
result file will contain a CREATE statement for a similar
Aria table, followed by the table data and ending with an
ALTER TABLE xxx ENGINE=S3.
• --create-options, -a
Include all MariaDB-specific table options in the CREATE
TABLE statements. Use --skip-create-options to disable.
• --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
Default authentication client-side plugin to use.
• --default-character-set=charset_name
Use charset_name as the default character set. If no
character set is specified, mysqldump uses utf8.
• --defaults-extra-file=filename
Set filename as the file to read default options from after
the global defaults files has been read. Must be given as
first option.
• --defaults-file=filename
Set filename as the file to read default options from,
override global defaults files. Must be given as first
option.
• --defaults-group-suffix=str,
Also read groups with a suffix of str. For example, since
mysqldump normally reads the [client] and [mysqldump] groups,
--defaults-group-suffix=x would cause it to also read the
groups [mysqldump_x] and [client_x].
• --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.
• --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]
Used for producing a dump file from a replication slave
server that can be used to set up another slave server with
the same master. Causes the binary log position and filename
of the master to be appended to the dumped data output.
Setting the value to 1 (the default) will print it as a
CHANGE MASTER command in the dumped data output; if set to 2,
that command will be prefixed with a comment symbol. This
option will turn --lock-all-tables on, unless --single-
transaction is specified too (in which case a global read
lock is only taken a short time at the beginning of the dump
- don't forget to read about --single-transaction below). In
all cases any action on logs will happen at the exact moment
of the dump. Option automatically turns --lock-tables off.
Using this option causes mysqldump to stop the slave SQL
thread before beginning the dump, and restart it again after
completion.
• --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.
• --first-slave
Removed in MariaDB 5.5. Use --lock-all-tables instead.
• --flashback, -B
Support flashback mode.
• --flush-logs, -F
Flush the MariaDB 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 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.
• --flush-privileges
Send a FLUSH PRIVILEGES statement to the server 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.
• --gtid
Available from MariaDB 10.0.13, and is used together with
--master-data and --dump-slave to more conveniently set up a
new GTID slave. It causes those options to output SQL
statements that configure the slave to use the global
transaction ID to connect to the master instead of old-style
filename/offset positions. The old-style positions are still
included in comments when --gtid is used; likewise the GTID
position is included in comments even if --gtid is not used.
• --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.
• --host=host_name, -h host_name
Dump data from the MariaDB server on the given host. The
default host is localhost.
• --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.
• --include-master-host-port
Add the MASTER_HOST and MASTER_PORT options for the CHANGE
MASTER TO statement when using the --dump-slave option for a
slave dump.
• --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.
• --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 allow
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.
Use --skip-lock-tables to disable.
• --log-error=file_name
Log warnings and errors by appending them to the named file.
The default is to do no logging.
• --log-queries
When restoring the dump, the server will, if logging is
turned on, log the queries to the general and slow query log.
Defaults to on; use --skip-log-queries to disable.
• --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 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. To do this, 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
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.
• --max-allowed-packet=length
Sets the maximum packet length to send to or receive from
server.
• --net-buffer-length=length
Sets the buffer size for TCP/IP and socket communication.
• --no-autocommit
Enclose the INSERT statements for each dumped table within
SET autocommit = 0 and COMMIT statements.
• --no-create-db, -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.
• --no-data, -d
Do not write any table row information (that is, do not dump
table contents). This is useful if you want to dump only the
CREATE TABLE statement for the table (for example, to create
an empty copy of the table by loading the dump file).
• --no-defaults
Do not read default options from any option file. This must
be given as the first argument.
• --no-set-names, -N
This has the same effect as --skip-set-charset.
• --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 MariaDB 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. You can use an option file to avoid
giving the password on the command line.
• --pipe, -W
On Windows, connect to the server via a named pipe. This
option applies only if the server supports named-pipe
connections.
• --plugin-dir
Directory for client-side plugins.
• --port=port_num, -P port_num
The TCP/IP port number to use for the connection. Forces
--protocol=tcp when specified on the command line without
other connection properties.
• --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.
• --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.
• --print-defaults
Print the program argument list and exit. This must be given
as the first argument.
• --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
Included 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 MariaDB account that has appropriate privileges for
the mysql database.
• --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 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 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.
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, you should combine the
--single-transaction option with --quick.
• --skip-add-drop-table
Disable the --add-drop-table option.
• --skip-add-locks
Disable the --add-locks option.
• --skip-comments
Disable the --comments option.
• --skip-compact
Disable the --compact option.
• --skip-disable-keys
Disable the --disable-keys option.
• --skip-extended-insert
Disable the --extended-insert option.
• --skip-opt
Disable the --opt option.
• --skip-quick
Disable the --quick option.
• --skip-quote-names
Disable the --quote-names option.
• --skip-set-charset
Disable the --set-charset option.
• --skip-triggers
Disable the --triggers option.
• --skip-tz-utc
Disable the --tz-utc 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. Forces
--protocol=socket when specified on the command line without
other connection properties; on Windows, forces
--protocol=pipe.
• --ssl
Enable SSL for connection (automatically enabled with other
flags). Disable with --skip-ssl.
• --ssl-ca=name
CA file in PEM format (check OpenSSL docs, implies --ssl).
• --ssl-capath=name
CA directory (check OpenSSL docs, implies --ssl).
• --ssl-cert=name
X509 cert in PEM format (check OpenSSL docs, implies --ssl).
• --ssl-cipher=name
SSL cipher to use (check OpenSSL docs, implies --ssl).
• --ssl-key=name
X509 key in PEM format (check OpenSSL docs, implies --ssl).
• --ssl-crl=name
Certificate revocation list (check OpenSSL docs, implies
--ssl).
• --ssl-crlpath=name
Certificate revocation list path (check OpenSSL docs, implies
--ssl).
• --ssl-verify-server-cert
Verify server's "Common Name" in its cert against hostname
used when connecting. This option is disabled by default.
• --system={all, users, plugins, udfs, servers, stats,
timezones}
Dump the system tables in the mysql database in a logical
form. This option is an empty set by default.
One or more options can be listed in comma separated list.
The options here are:
• all - an alias to enabling all of the below options.
• users - the users, roles and their grants outputed as
CREATE USER, CREATE ROLE, GRANT, and SET DEFAULT ROLE
(ALTER USER for MySQL-8.0+).
• plugins - active plugins of the server outputed as
INSTALL PLUGIN.
• udfs - user define functions outputed as CREATE FUNCTION.
• servers - remote (federated) servers as CREATE SERVER.
• stats - statistics tables, InnoDB and Engine Independent
Table Statistics (EITS), are dumped as REPLACE INTO (or
INSERT IGNORE if --insert-into is specified) statements
without (re)creating tables.
• timezones - timezone related system tables dumped as
REPLACE INTO (or INSERT IGNORE if --insert-into is
specified) statements without (re)creating tables.
The format of the output is affected by --replace and
--insert-into. The --replace option will output CREATE OR
REPLACE forms of SQL, and also DROP IF EXISTS prior to
CREATE, if a CREATE OR REPLACE option isn't available.
With --system=user (or all), and --replace, SQL is generated
to generate an error if attempting to import the dump with a
connection user that is being replaced within the dump.
The --insert-into option will cause CREATE IF NOT EXIST forms
of SQL to generated if available.
For stats, and timezones, --replace and --insert-into have
the usual effects.
Enabling specific options here will cause the relevant tables
in the mysql database to be ignored when dumping the mysql
database or --all-databases.
To help in migrating from MySQL to MariaDB, this option is
designed to be able to dump system information from MySQL-5.7
and 8.0 servers. SQL generated is also experimentally
compatible with MySQL-5.7/8.0. Mappings of implementation
specific grants/plugins isn't always one-to-one however
between MariaDB and MySQL and will require manual changes.
• --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 MariaDB 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>
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 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 MariaDB server is at least
this large.
A common use of mysqldump is for making a backup of an entire
database:
shell> mysqldump db_name > backup-file.sql
You can load the dump file back into the server like this:
shell> mysql db_name < backup-file.sql
Or like this:
shell> mysql -e "source /path-to-backup/backup-file.sql" db_name
mysqldump is also very useful for populating databases by copying
data from one MariaDB 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 MariaDB
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 MariaDB 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 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.
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.
