MYSQLDUMP(1) | MySQL Database System | MYSQLDUMP(1) |
NAME¶
mysqldump - a database backup program
SYNOPSIS¶
mysqldump [options] [db_name [tbl_name ...]]
DESCRIPTION¶
The mysqldump client utility performs logical backups, producing a set of SQL statements that can be executed to reproduce the original database object definitions and table data. It dumps one or more MySQL databases for backup or transfer to another SQL server. The mysqldump command can also generate output in CSV, other delimited text, or XML format.
Tip
Consider using the MySQL Shell dump utilities[1], which provide parallel dumping with multiple threads, file compression, and progress information display, as well as cloud features such as Oracle Cloud Infrastructure Object Storage streaming, and MySQL Database Service compatibility checks and modifications. Dumps can be easily imported into a MySQL Server instance or a MySQL Database Service DB System using the MySQL Shell load dump utilities[2]. Installation instructions for MySQL Shell can be found here[3].
mysqldump requires at least the SELECT privilege for dumped tables, SHOW VIEW for dumped views, TRIGGER for dumped triggers, LOCK TABLES if the --single-transaction option is not used, and (as of MySQL 8.0.21) PROCESS if the --no-tablespaces option is not used. Certain options might require other privileges as noted in the option descriptions.
To reload a dump file, you must have the privileges required to execute the statements that it contains, such as the appropriate CREATE privileges for objects created by those statements.
mysqldump output can include ALTER DATABASE statements that change the database collation. These may be used when dumping stored programs to preserve their character encodings. To reload a dump file containing such statements, the ALTER privilege for the affected database is required.
Note
A dump made using PowerShell on Windows with output redirection creates a file that has UTF-16 encoding:
mysqldump [options] > dump.sql
However, UTF-16 is not permitted as a connection character set (see the section called “Impermissible Client Character Sets”), so the dump file cannot be loaded correctly. To work around this issue, use the --result-file option, which creates the output in ASCII format:
mysqldump [options] --result-file=dump.sql
It is not recommended to load a dump file when GTIDs are enabled on the server (gtid_mode=ON), if your dump file includes system tables. mysqldump issues DML instructions for the system tables which use the non-transactional MyISAM storage engine, and this combination is not permitted when GTIDs are enabled. 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 so that they can be restored quickly.
If your tables are primarily InnoDB tables, or if you have a mix of InnoDB and MyISAM tables, consider using mysqlbackup, which is available as part of MySQL Enterprise. This tool provides high performance for InnoDB backups with minimal disruption; it can also back up tables from MyISAM and other storage engines; it also provides a number of convenient options to accommodate different backup scenarios. See Section 30.2, “MySQL Enterprise Backup Overview”.
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”. Invocation Syntax
There are in general three ways to use mysqldump—in order to dump a set of one or more tables, a set of one or more complete databases, or an entire MySQL server—as shown here:
mysqldump [options] db_name [tbl_name ...] mysqldump [options] --databases db_name ... mysqldump [options] --all-databases
To dump entire databases, do not name any tables following db_name, or use the --databases or --all-databases option.
To see a list of the options your version of mysqldump supports, issue the command mysqldump --help. Option Syntax - Alphabetical Summary
mysqldump supports the following options, which can be specified on the command line or in the [mysqldump] and [client] groups of an option file. For information about option files used by MySQL programs, see Section 4.2.2.2, “Using Option Files”. Connection Options
The mysqldump command logs into a MySQL server to extract information. The following options specify how to connect to the MySQL server, either on the same machine or a remote system.
As of MySQL 8.0.18, this option is deprecated. Expect it to be removed in a future version of MySQL. See the section called “Configuring Legacy Connection Compression”.
For more information, see Section 4.2.8, “Connection Compression Control”.
This option was added in MySQL 8.0.18.
If --server-public-key-path=file_name is given and specifies a valid public key file, it takes precedence over --get-server-public-key.
For information about the caching_sha2_password plugin, see Section 6.4.1.2, “Caching SHA-2 Pluggable Authentication”.
For additional information about this and other option-file options, see Section 4.2.2.3, “Command-Line Options that Affect Option-File Handling”.
Specifying a password on the command line should be considered insecure. To avoid giving the password on the command line, use an option file. See Section 6.1.2.1, “End-User Guidelines for Password Security”.
To explicitly specify that there is no password and that mysqldump should not prompt for one, use the --skip-password option.
Specifying a password on the command line should be considered insecure. To avoid giving the password on the command line, use an option file. See Section 6.1.2.1, “End-User Guidelines for Password Security”.
To explicitly specify that there is no password and that mysqldump should not prompt for one, use the --skip-password1 option.
--password1 and --password are synonymous, as are --skip-password1 and --skip-password.
If --server-public-key-path=file_name is given and specifies a valid public key file, it takes precedence over --get-server-public-key.
For sha256_password, this option applies only if MySQL was built using OpenSSL.
For information about the sha256_password and caching_sha2_password plugins, see Section 6.4.1.3, “SHA-256 Pluggable Authentication”, and Section 6.4.1.2, “Caching SHA-2 Pluggable Authentication”.
On Windows, this option applies only if the server was started with the named_pipe system variable enabled to support named-pipe connections. In addition, the user making the connection must be a member of the Windows group specified by the named_pipe_full_access_group system variable.
These --ssl-fips-mode values are permitted:
Note
If the OpenSSL FIPS Object Module is not available, the only permitted value for --ssl-fips-mode is OFF. In this case, setting --ssl-fips-mode to ON or STRICT causes the client to produce a warning at startup and to operate in non-FIPS mode.
This option was added in MySQL 8.0.16.
If you are using the Rewriter plugin with MySQL 8.0.31 or later, you should grant this user the SKIP_QUERY_REWRITE privilege.
For more information, see Section 4.2.8, “Connection Compression Control”.
This option was added in MySQL 8.0.18.
These options are used to control which option files to read.
For additional information about this and other option-file options, see Section 4.2.2.3, “Command-Line Options that Affect Option-File Handling”.
Exception: Even with --defaults-file, client programs read .mylogin.cnf.
For additional information about this and other option-file options, see Section 4.2.2.3, “Command-Line Options that Affect Option-File Handling”.
For additional information about this and other option-file options, see Section 4.2.2.3, “Command-Line Options that Affect Option-File Handling”.
The exception is that the .mylogin.cnf file is read in all cases, if it exists. This permits passwords to be specified in a safer way than on the command line even when --no-defaults is used. To create .mylogin.cnf, use the mysql_config_editor utility. See mysql_config_editor(1).
For additional information about this and other option-file options, see Section 4.2.2.3, “Command-Line Options that Affect Option-File Handling”.
For additional information about this and other option-file options, see Section 4.2.2.3, “Command-Line Options that Affect Option-File Handling”.
Usage scenarios for mysqldump include setting up an entire new MySQL instance (including database tables), and replacing data inside an existing instance with existing databases and tables. The following options let you specify which things to tear down and set up when restoring a dump, by encoding various DDL statements within the dump file.
Note
In MySQL 8.0, the mysql schema is considered a system schema that cannot be dropped by end users. If --add-drop-database is used with --all-databases or with --databases where the list of schemas to be dumped includes mysql, the dump file contains a DROP DATABASE `mysql` statement that causes an error when the dump file is reloaded.
Instead, to use --add-drop-database, use --databases with a list of schemas to be dumped, where the list does not include mysql.
Note
This option does not exclude statements creating log file groups or tablespaces from mysqldump output; however, you can use the --no-tablespaces option for this purpose.
The following options print debugging information, encode debugging information in the dump file, or let the dump operation proceed regardless of potential problems.
This option is available only if MySQL was built using WITH_DEBUG. MySQL release binaries provided by Oracle are not built using this option.
This option is available only if MySQL was built using WITH_DEBUG. MySQL release binaries provided by Oracle are not built using this option.
This option is available only if MySQL was built using WITH_DEBUG. MySQL release binaries provided by Oracle are not built using this option.
-- 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.
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.
If the --ignore-error option is also given to ignore specific errors, --force takes precedence.
The following options display information about the mysqldump command itself.
The following options change how the mysqldump command represents character data with national language settings.
The mysqldump command is frequently used to create an empty instance, or an instance including data, on a replica server in a replication configuration. The following options apply to dumping and restoring data on replication source servers and replicas.
Note
Inconsistencies in the sequence of transactions from the relay log which have been executed can cause the wrong position to be used. See Section 17.5.1.34, “Replication and Transaction Inconsistencies” for more information.
Warning
--dump-replica and --dump-slave should not be used if the server where the dump is going to be applied uses gtid_mode=ON and SOURCE_AUTO_POSITION=1 or MASTER_AUTO_POSITION=1.
--dump-replica and --dump-slave cause mysqldump to stop the replication SQL thread before the dump and restart it again after.
--dump-replica and --dump-slave send a SHOW REPLICA STATUS statement to the server to obtain information, so they require privileges sufficient to execute that statement.
--apply-replica-statements and --include-source-host-port options can be used in conjunction with --dump-replica and --dump-slave.
If the option value is 2, the CHANGE REPLICATION SOURCE TO | 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.
--source-data and --master-data send a SHOW MASTER STATUS statement to the server to obtain information, so they require privileges sufficient to execute that statement. This option also requires the RELOAD privilege and the binary log must be enabled.
--source-data and --master-data automatically turn off --lock-tables. They also turn 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 replica by dumping an existing replica of the source, using the --dump-replica or --dump-slave option, which overrides --source-data and --master-data and causes them to be ignored.
If you do not set the --set-gtid-purged option, the default is that a SET @@GLOBAL.gtid_purged statement is included in the dump output if GTIDs are enabled on the server you are backing up, and the set of GTIDs in the global value of the gtid_executed system variable is not empty. A SET @@SESSION.sql_log_bin=0 statement is also included if GTIDs are enabled on the server.
You can either replace the value of gtid_purged with a specified GTID set, or add a plus sign (+) to the statement to append a specified GTID set to the GTID set that is already held by gtid_purged. The SET @@GLOBAL.gtid_purged statement recorded by mysqldump includes a plus sign (+) in a version-specific comment, such that MySQL 8.0 (and later) adds the GTID set from the dump file to the existing gtid_purged value.
It is important to note that the value that is included by mysqldump for the SET @@GLOBAL.gtid_purged statement includes the GTIDs of all transactions in the gtid_executed set on the server, even those that changed suppressed parts of the database, or other databases on the server that were not included in a partial dump. This can mean that after the gtid_purged value has been updated on the server where the dump file is replayed, GTIDs are present that do not relate to any data on the target server. If you do not replay any further dump files on the target server, the extraneous GTIDs do not cause any problems with the future operation of the server, but they make it harder to compare or reconcile GTID sets on different servers in the replication topology. If you do replay a further dump file on the target server that contains the same GTIDs (for example, another partial dump from the same origin server), any SET @@GLOBAL.gtid_purged statement in the second dump file fails. In this case, either remove the statement manually before replaying the dump file, or output the dump file without the statement.
Using this option with the --single-transaction option can lead to inconsistencies in the output. If --set-gtid-purged=ON is required, it can be used with --lock-all-tables, but this can prevent parallel queries while mysqldump is being run.
If the SET @@GLOBAL.gtid_purged statement would not have the desired result on your target server, you can exclude the statement from the output, or (from MySQL 8.0.17) include it but comment it out so that it is not actioned automatically. You can also include the statement but manually edit it in the dump file to achieve the desired result.
The possible values for the --set-gtid-purged option are as follows:
AUTO
OFF
ON
COMMENTED
The following options specify how to represent the entire dump file or certain kinds of data in the dump file. They also control whether certain optional information is written to the dump file.
This option should be used on Windows to prevent newline \n characters from being converted to \r\n carriage return/newline sequences.
This option was added in MySQL 8.0.18. Attempting a mysqldump operation with the --show-create-skip-secondary-engine option on a release prior to MySQL 8.0.18 that does not support the show_create_table_skip_secondary_engine variable causes an error.
Note
This option should be used only when mysqldump is run on the same machine as the mysqld server. Because the server creates *.txt files in the directory that you specify, the directory must be writable by the server and the MySQL account that you use must have the FILE privilege. Because mysqldump creates *.sql in the same directory, it must be writable by your system login account.
Column values are converted to the character set specified by the --default-character-set option.
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> |
(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 CLIENT OPTIONS”.)
XML output from mysqldump includes the XML namespace, as shown here:
$> 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>
The following options control which kinds of schema objects are written to the dump file: by category, such as triggers or events; by name, for example, choosing which databases and tables to dump; or even filtering rows from the table data using a WHERE clause.
Note
See the --add-drop-database description for information about an incompatibility of that option with --all-databases.
This option may be used to dump the performance_schema database, which normally is not dumped even with the --all-databases option. (Also use the --skip-lock-tables option.)
Note
See the --add-drop-database description for information about an incompatibility of that option with --databases.
The output generated by using --events contains CREATE EVENT statements to create the events.
The output generated by using --routines contains CREATE PROCEDURE and CREATE FUNCTION statements to create the routines.
To be able to dump a table's triggers, you must have the TRIGGER privilege for the table.
Multiple triggers are permitted. mysqldump dumps triggers in activation order so that when the dump file is reloaded, triggers are created in the same activation order. However, if a mysqldump dump file contains multiple triggers for a table that have the same trigger event and action time, an error occurs for attempts to load the dump file into an older server that does not support multiple triggers. (For a workaround, see Downgrade Notes[4]; you can convert triggers to be compatible with older servers.)
Examples:
--where="user='jimf'" -w"userid>1" -w"userid<1"
The following options are the most relevant for the performance particularly of the restore operations. For large data sets, restore operation (processing the INSERT statements in the dump file) is the most time-consuming part. When it is urgent to restore data quickly, plan and test the performance of this stage in advance. For restore times measured in hours, you might prefer an alternative backup and restore solution, such as MySQL Enterprise Backup for InnoDB-only and mixed-use databases.
Performance is also affected by the transactional options, primarily for the dump operation.
Note
The value of this option is specific to mysqldump and should not be confused with the MySQL server's max_allowed_packet system variable; the server value cannot be exceeded by a single packet from mysqldump, regardless of any setting for the mysqldump option, even if the latter is larger.
You can use --mysqld-long-query-time to specify a session value from 0 (meaning that every query from mysqldump is logged to the slow query log) to 31536000, which is 365 days in seconds. For mysqldump’s option, you can only specify whole seconds. When you do not specify this option, the server’s global setting applies to mysqldump’s queries.
Because the --opt option is enabled by default, you only specify its converse, the --skip-opt to turn off several default settings. See the discussion of mysqldump option groups for information about selectively enabling or disabling a subset of the options affected by --opt.
The following options trade off the performance of the dump operation, against the reliability and consistency of the exported data.
Because the dump file contains a FLUSH PRIVILEGES statement, reloading the file requires privileges sufficient to execute that statement.
Note
For upgrades to MySQL 5.7 or higher from older versions, do not use --flush-privileges. For upgrade instructions in this case, see Section 2.11.4, “Changes in MySQL 8.0”.
Because --lock-tables locks tables for each database separately, this option does not guarantee that the tables in the dump file are logically consistent between databases. Tables in different databases may be dumped in completely different states.
Some options, such as --opt, automatically enable --lock-tables. If you want to override this, use --skip-lock-tables at the end of the option list.
This option applies only if the server was started with the shared_memory system variable enabled to support shared-memory connections.
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.
Using --single-transaction together with the --set-gtid-purged option is not recommended; doing so can lead to inconsistencies in the output of mysqldump.
To dump large tables, combine the --single-transaction option with the --quick option.
When you selectively enable or disable the effect of a group option, order is important because options are processed first to last. For example, --disable-keys --lock-tables --skip-opt would not have the intended effect; it is the same as --skip-opt by itself. Examples
To make a backup of an entire database:
mysqldump db_name > backup-file.sql
To load the dump file back into the server:
mysql db_name < backup-file.sql
Another way to reload the dump file:
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:
mysqldump --opt db_name | mysql --host=remote_host -C db_name
You can dump several databases with one command:
mysqldump --databases db_name1 [db_name2 ...] > my_databases.sql
To dump all databases, use the --all-databases option:
mysqldump --all-databases > all_databases.sql
For InnoDB tables, mysqldump provides a way of making an online backup:
mysqldump --all-databases --master-data --single-transaction > all_databases.sql or from MySQL 8.0.26: mysqldump --all-databases --source-data --single-transaction > all_databases.sql
This backup acquires a global read lock on all tables (using FLUSH TABLES WITH READ LOCK) at the beginning of the dump. As soon as this lock has been acquired, the binary log coordinates are read and the lock is released. If long updating statements are running when the FLUSH statement is issued, the MySQL server may get stalled until those statements finish. After that, the dump becomes lock free and does not disturb reads and writes on the tables. If the update statements that the MySQL server receives are short (in terms of execution time), the initial lock period should not be noticeable, even with many updates.
For point-in-time recovery (also known as “roll-forward,” when you need to restore an old backup and replay the changes that happened since that backup), it is often useful to rotate the binary log (see Section 5.4.4, “The Binary Log”) or at least know the binary log coordinates to which the dump corresponds:
mysqldump --all-databases --master-data=2 > all_databases.sql or from MySQL 8.0.26: mysqldump --all-databases --source-data=2 > all_databases.sql
Or:
mysqldump --all-databases --flush-logs --master-data=2 > all_databases.sql or from MySQL 8.0.26: mysqldump --all-databases --flush-logs --source-data=2 > all_databases.sql
The --source-data or --master-data option can be used simultaneously with the --single-transaction option, 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”.
mysqldump does not dump the performance_schema or sys schema by default. To dump any of these, name them explicitly on the command line. You can also name them with the --databases option. For performance_schema, also use the --skip-lock-tables option.
mysqldump does not dump the INFORMATION_SCHEMA schema.
mysqldump does not dump InnoDB CREATE TABLESPACE statements.
mysqldump does not dump the NDB Cluster ndbinfo information database.
mysqldump includes statements to recreate the general_log and slow_query_log tables for dumps of the mysql database. Log table contents are not dumped.
If you encounter problems backing up views due to insufficient privileges, see Section 25.9, “Restrictions on Views” for a workaround.
COPYRIGHT¶
Copyright © 1997, 2022, Oracle and/or its affiliates.
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/.
NOTES¶
- 1.
- MySQL Shell dump utilities
- 2.
- MySQL Shell load dump utilities
- 3.
- here
- 4.
- Downgrade Notes
SEE ALSO¶
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¶
Oracle Corporation (http://dev.mysql.com/).
11/26/2022 | MySQL 8.0 |