The default is 24MB, the maximum is 1GB. When creating multiple-row INSERT statements as with the --extended-insert or --opt option , mysqldump creates rows up to --net-buffer-length bytes long. Enable large tables to be dumped by setting --max-allowed-packet to its maximum value and network read and write timeouts to a large value.
To disable it, use --skip-network-timeout. This option, enabled by default, is shorthand for the combination of --add-drop-table --add-locks --create-options --disable-keys --extended-insert --lock-tables --quick --set-charset. It gives a fast dump operation and produces a dump file that can be reloaded into a MySQL server quickly.
Because the --opt option is enabled by default, you only specify its converse, the --skip-opt to turn off several default settings. See the discussion of mysqldump option groups for information about selectively enabling or disabling a subset of the options affected by --opt. 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.
See the description for the --opt option. The following options trade off the performance of the dump operation, against the reliability and consistency of the exported data. This results in faster inserts when the dump file is reloaded. See Section 8. Flush the MySQL server log files before starting the dump. 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 , --source-data or --master-data , or --single-transaction.
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 , --source-data or --master-data , or --single-transaction. 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. For upgrades to MySQL 5. For upgrade instructions in this case, see Section 2. 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. For each dumped database, lock all tables to be dumped before dumping them. For transactional tables such as InnoDB , --single-transaction is a much better option than --lock-tables because it does not need to lock the tables at all.
Because --lock-tables locks tables for each database separately, this option does not guarantee that the tables in the dump file are logically consistent between databases. Tables in different databases may be dumped in completely different states.
Some options, such as --opt , automatically enable --lock-tables. If you want to override this, use --skip-lock-tables at the end of the option list. Dump each table's rows sorted by its primary key, or by its first unique index, if such an index exists. On Windows, the shared-memory name to use for connections made using shared memory to a local server. The shared-memory name is case-sensitive. When using this option, you should keep in mind that only InnoDB tables are dumped in a consistent state.
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.
To dump large tables, combine the --single-transaction option with the --quick option. The --opt option turns on several settings that work together to perform a fast dump operation. All of these settings are on by default, because --opt is on by default. Thus you rarely if ever specify --opt.
Instead, you can turn these settings off as a group by specifying --skip-opt , the optionally re-enable certain settings by specifying the associated options later on the command line. The --compact option turns off several settings that control whether optional statements and comments appear in the output. Again, you can follow this option with other options that re-enable certain settings, or turn all the settings on by using the --skip-compact form.
When you selectively enable or disable the effect of a group option, order is important because options are processed first to last. For example, --disable-keys --lock-tables --skip-opt would not have the intended effect; it is the same as --skip-opt by itself. To dump all databases, use the --all-databases option:.
For InnoDB tables, mysqldump provides a way of making an online backup:. As soon as this lock has been acquired, the binary log coordinates are read and the lock is released. 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.
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. 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. To dump any of these, name them explicitly on the command line.
You can also name them with the --databases option. Log table contents are not dumped. If you encounter problems backing up views due to insufficient privileges, see Section Using Options on the Command Line. Using Options to Set Program Variables. Command Options for Connecting to the Server. Connection Transport Protocols. Connection Compression Control.
Setting Environment Variables. Server and Server-Startup Programs. Installation-Related Programs. Administrative and Utility Programs. Other myisamchk Options. Obtaining Table Information with myisamchk. Specifying the mysqlbinlog Server ID.
Program Development Utilities. InnoDB Cluster. InnoDB ReplicaSet. Error Messages and Common Problems. MySQL 8. If you are not currently backing up your data, you need to do so immediately. Romain Bourdon typically does not release WampServer EXE files for download because they are bundled together inside of a software installer. The installer's task is to ensure that all correct verifications have been made before installing and placing mysqldump.
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Some options, like --lines-terminated-by , accept a string. The string can be quoted, if necessary. For example, on Unix systems this is the option to enclose fields within double quotes:.
An alternative to specify the hexadecimal value of a character. For example, the following syntax works on any platform:. In addition to reading options from the command-line, mysqldump can also read options from option files.
If an unknown option is provided to mysqldump in an option file, then it is ignored. The following options relate to how MariaDB command-line tools handles option files. They must be given as the first argument on the command-line:. In MariaDB That is still performed by the server option file parsing code.
See MDEV for more information. The output from the mysql client when run using the --xml option also follows the preceding rules. To restore a backup created with mysqldump, use the mysql client to import the dump, for example:. To dump all databases, use the --all-databases option:. As soon as this lock has been acquired, the binary log coordinates are read and the lock is released.
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. 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.
Knowledge Base Contact Login Search. Buffering mysqldump in MariaDB MariaDB starting with Option Description --all Deprecated. Use --create-options instead. This will be same as --databases with all databases selected.
Use --skip-add-locks to disable. This works by prefixing each column name with the table name. Disable with --skip-comments. Enables the --skip-add-drop-table , --skip-add-locks , --skip-comments , --skip-disable-keys , and --skip-set-charset options.
One can use several modes separated by commas. 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.
Both client and server must support compression for this to work. Use --skip-create-options to disable. 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. If using a non-debug version, mysqldump will catch this and exit.
If no character set is specified, until MariaDB Must be given as the first argument. This option automatically enables --master-data.
This makes loading the dump file faster because the indexes are created after all rows are inserted. Disable with --skip-disable-keys. The default is --dump-date include the date in the comment. Causes the binary log position and filename of the primary to be appended to the dumped data output.
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 replica SQL thread before beginning the dump, and restart it again after completion.
This results in a smaller dump file and speeds up inserts when the file is reloaded. Defaults to on; use --skip-extended-insert to disable. Use --lock-all-tables instead. The exception is when using --lock-all-tables or --master-data : In this case, the logs are flushed only once, corresponding to the moment all tables are locked. If you want your dump and the log flush to happen at the same exact moment, you should use --flush-logs together with either --lock-all-tables or --master-data.
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. 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.
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