4.5.4. mysqldump — A Database Backup Program

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 Section 4.6.9, “mysqlhotcopy — A Database Backup Program”.

There are three general ways to invoke mysqldump:

shell> mysqldump [options] db_name [tbl_name ...]
shell> mysqldump [options] --databases db_name ...
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.

mysqldump does not dump the INFORMATION_SCHEMA database by default. mysqldump dumps INFORMATION_SCHEMA only if you name it explicitly on the command line, although currently you must also use the --skip-lock-tables option. Before MySQL 5.5 mysqldump silently ignores INFORMATION_SCHEMA even if you name it explicitly on the command line.

mysqldump does not dump the performance_schema database.

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:

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:

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.

For additional information about mysqldump, see Section 6.4, “Using mysqldump for Backups”.

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 files described at Section 4.2.3.3.1, “Command-Line Options that Affect Option-File Handling”.

Table 4.5. mysqldump Options

FormatOption FileDescriptionIntroductionDeprecatedRemoved
--add-drop-databaseadd-drop-databaseAdd a DROP DATABASE statement before each CREATE DATABASE statement   
--add-drop-tableadd-drop-tableAdd a DROP TABLE statement before each CREATE TABLE statement   
--add-locksadd-locksSurround each table dump with LOCK TABLES and UNLOCK TABLES statements   
--all-databasesall-databasesDump all tables in all databases   
--allow-keywordsallow-keywordsAllow creation of column names that are keywords   
--apply-slave-statementsapply-slave-statementsInclude STOP SLAVE prior to CHANGE MASTER statement and START SLAVE at end of output5.5.3  
--bind-address=ip_addressbind-addressUse the specified network interface to connect to the MySQL Server5.5.8  
--commentscommentsAdd comments to the dump file   
--compactcompactProduce more compact output   
--compatible=name[,name,...]compatibleProduce output that is more compatible with other database systems or with older MySQL servers   
--complete-insertcomplete-insertUse complete INSERT statements that include column names   
--create-optionscreate-optionsInclude all MySQL-specific table options in CREATE TABLE statements   
--databasesdatabasesDump several databases   
--debug[=debug_options]debugWrite a debugging log   
--debug-checkdebug-checkPrint debugging information when the program exits   
--debug-infodebug-infoPrint debugging information, memory and CPU statistics when the program exits   
--default-auth=plugindefault-auth=pluginThe authentication plugin to use5.5.9  
--default-character-set=charset_namedefault-character-setUse charset_name as the default character set   
--delayed-insertdelayed-insertWrite INSERT DELAYED statements rather than INSERT statements   
--delete-master-logsdelete-master-logsOn a master replication server, delete the binary logs after performing the dump operation   
--disable-keysdisable-keysFor each table, surround the INSERT statements with statements to disable and enable keys   
--dump-datedump-dateInclude dump date as "Dump completed on" comment if --comments is given   
--dump-slave[=value]dump-slaveInclude CHANGE MASTER statement that lists binary log coordinates of slave's master5.5.3  
--eventseventsDump events from the dumped databases   
--extended-insertextended-insertUse multiple-row INSERT syntax that include several VALUES lists   
--fields-enclosed-by=stringfields-enclosed-byThis option is used with the --tab option and has the same meaning as the corresponding clause for LOAD DATA INFILE   
--fields-escaped-byfields-escaped-byThis option is used with the --tab option and has the same meaning as the corresponding clause for LOAD DATA INFILE   
--fields-optionally-enclosed-by=stringfields-optionally-enclosed-byThis option is used with the --tab option and has the same meaning as the corresponding clause for LOAD DATA INFILE   
--fields-terminated-by=stringfields-terminated-byThis option is used with the --tab option and has the same meaning as the corresponding clause for LOAD DATA INFILE   
--first-slavefirst-slaveDeprecated; use --lock-all-tables instead  5.5.3
--flush-logsflush-logsFlush the MySQL server log files before starting the dump   
--flush-privilegesflush-privilegesEmit a FLUSH PRIVILEGES statement after dumping the mysql database   
--help Display help message and exit   
--hex-blobhex-blobDump binary columns using hexadecimal notation (for example, 'abc' becomes 0x616263)   
--hosthostHost to connect to (IP address or hostname)   
--ignore-table=db_name.tbl_nameignore-tableDo not dump the given table   
--include-master-host-portinclude-master-host-portInclude MASTER_HOST/MASTER_PORT options in CHANGE MASTER statement produced with --dump-slave5.5.3  
--insert-ignoreinsert-ignoreWrite INSERT IGNORE statements rather than INSERT statements   
--lines-terminated-by=stringlines-terminated-byThis option is used with the --tab option and has the same meaning as the corresponding clause for LOAD DATA INFILE   
--lock-all-tableslock-all-tablesLock all tables across all databases   
--lock-tableslock-tablesLock all tables before dumping them   
--log-error=file_namelog-errorAppend warnings and errors to the named file   
--master-data[=value]master-dataWrite the binary log file name and position to the output   
--max_allowed_packet=valuemax_allowed_packetThe maximum packet length to send to or receive from the server   
--net_buffer_length=valuenet_buffer_lengthThe buffer size for TCP/IP and socket communication   
--no-autocommitno-autocommitEnclose the INSERT statements for each dumped table within SET autocommit = 0 and COMMIT statements   
--no-create-dbno-create-dbThis option suppresses the CREATE DATABASE statements   
--no-create-infono-create-infoDo not write CREATE TABLE statements that re-create each dumped table   
--no-datano-dataDo not dump table contents   
--no-set-namesno-set-namesSame as --skip-set-charset   
--no-tablespacesno-tablespacesDo not write any CREATE LOGFILE GROUP or CREATE TABLESPACE statements in output   
--optoptShorthand for --add-drop-table --add-locks --create-options --disable-keys --extended-insert --lock-tables --quick --set-charset.   
--order-by-primaryorder-by-primaryDump each table's rows sorted by its primary key, or by its first unique index   
--password[=password]passwordThe password to use when connecting to the server   
--pipe On Windows, connect to server using a named pipe   
--plugin-dir=pathplugin-dir=pathThe directory where plugins are located5.5.9  
--port=port_numportThe TCP/IP port number to use for the connection   
--quickquickRetrieve rows for a table from the server a row at a time   
--quote-namesquote-namesQuote identifiers within backtick characters   
--replacereplaceWrite REPLACE statements rather than INSERT statements   
--result-file=fileresult-fileDirect output to a given file   
--routinesroutinesDump stored routines (procedures and functions) from the dumped databases   
--set-charsetset-charsetAdd SET NAMES default_character_set to the output   
--single-transactionsingle-transactionThis option issues a BEGIN SQL statement before dumping data from the server   
--skip-add-drop-tableskip-add-drop-tableDo not add a DROP TABLE statement before each CREATE TABLE statement   
--skip-add-locksskip-add-locksDo not add locks   
--skip-commentsskip-commentsDo not add comments to the dump file   
--skip-compactskip-compactDo not produce more compact output   
--skip-disable-keysskip-disable-keysDo not disable keys   
--skip-extended-insertskip-extended-insertTurn off extended-insert   
--skip-optskip-optTurn off the options set by --opt   
--skip-quickskip-quickDo not retrieve rows for a table from the server a row at a time   
--skip-quote-namesskip-quote-namesDo not quote identifiers   
--skip-set-charsetskip-set-charsetSuppress the SET NAMES statement   
--skip-triggersskip-triggersDo not dump triggers   
--skip-tz-utcskip-tz-utcTurn off tz-utc   
--ssl-ca=file_namessl-caThe path to a file that contains a list of trusted SSL CAs   
--ssl-capath=directory_namessl-capathThe path to a directory that contains trusted SSL CA certificates in PEM format   
--ssl-cert=file_namessl-certThe name of the SSL certificate file to use for establishing a secure connection   
--ssl-cipher=cipher_listssl-cipherA list of allowable ciphers to use for SSL encryption   
--ssl-key=file_namessl-keyThe name of the SSL key file to use for establishing a secure connection   
--ssl-verify-server-certssl-verify-server-certThe server's Common Name value in its certificate is verified against the host name used when connecting to the server   
--tab=pathtabProduce tab-separated data files   
--tablestablesOverride the --databases or -B option   
--triggerstriggersDump triggers for each dumped table   
--tz-utctz-utcAdd SET TIME_ZONE='+00:00' to the dump file   
--user=user_nameuserThe MySQL user name to use when connecting to the server   
--verbose Verbose mode   
--version Display version information and exit   
--where='where_condition'whereDump only rows selected by the given WHERE condition   
--xmlxmlProduce XML output   
  • --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-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 7.2.2.1, “Speed of INSERT Statements”.

  • --all-databases, -A

    Dump all tables in all databases. This is the same as using the --databases option and naming all the databases on the command line.

  • --all-tablespaces, -Y

    Adds to a table dump all SQL statements needed to create any tablespaces used by an NDBCLUSTER table. This information is not otherwise included in the output from mysqldump. This option is currently relevant only to MySQL Cluster tables.

  • --allow-keywords

    Permit creation of column names that are keywords. This works by prefixing each column name with the table name.

  • --apply-slave-statements

    For a slave dump produced with the --dump-slave option, add a STOP SLAVE statement before the CHANGE MASTER TO statement and a START SLAVE statement at the end of the output. This option was added in MySQL 5.5.3.

  • --bind-address=ip_address

    On a computer having multiple network interfaces, this option can be used to select which interface is employed when connecting to the MySQL server.

    This option is supported beginning with MySQL 5.5.8.

  • --character-sets-dir=path

    The directory where character sets are installed. See Section 9.5, “Character Set Configuration”.

  • --comments, -i

    Write additional information in the dump file such as program version, server version, and host. This option is enabled by default. To suppress this additional information, use --skip-comments.

  • --compact

    Produce more compact output. This option enables the --skip-add-drop-table, --skip-add-locks, --skip-comments, --skip-disable-keys, and --skip-set-charset options.

  • --compatible=name

    Produce output that is more compatible with other database systems or with older MySQL servers. The value of name can be ansi, mysql323, mysql40, postgresql, oracle, mssql, db2, maxdb, no_key_options, no_table_options, or no_field_options. To use several values, separate them by commas. These values have the same meaning as the corresponding options for setting the server SQL mode. See Section 5.1.7, “Server SQL Modes”.

    This option does not guarantee compatibility with other servers. It only enables those SQL mode values that are currently available for making dump output more compatible. For example, --compatible=oracle does not map data types to Oracle types or use Oracle comment syntax.

    This option requires a server version of 4.1.0 or higher. With older servers, it does nothing.

  • --complete-insert, -c

    Use complete INSERT statements that include column names.

  • --compress, -C

    Compress all information sent between the client and the server if both support compression.

  • --create-options

    Include all MySQL-specific table options in the CREATE TABLE statements.

  • --databases, -B

    Dump several databases. Normally, mysqldump treats the first name argument on the command line as a database name and following names as table names. With this option, it treats all name arguments as database names. CREATE DATABASE and USE statements are included in the output before each new database.

  • --debug[=debug_options], -# [debug_options]

    Write a debugging log. A typical debug_options string is 'd:t:o,file_name'. The default value is 'd:t:o,/tmp/mysqldump.trace'.

  • --debug-check

    Print some debugging information when the program exits.

  • --debug-info

    Print debugging information and memory and CPU usage statistics when the program exits.

  • --default-auth=plugin

    The client-side authentication plugin to use. See Section 5.5.6, “Pluggable Authentication”.

    This option was added in MySQL 5.5.9.

  • --default-character-set=charset_name

    Use charset_name as the default character set. See Section 9.5, “Character Set Configuration”. If no character set is specified, mysqldump uses utf8, and earlier versions use latin1.

  • --delayed-insert

    Write INSERT DELAYED statements rather than INSERT statements.

  • --delete-master-logs

    On a master replication server, delete the binary logs by sending a PURGE BINARY LOGS statement to the server after performing the dump operation. This option automatically enables --master-data.

  • --disable-keys, -K

    For each table, surround the INSERT statements with /*!40000 ALTER TABLE tbl_name DISABLE KEYS */; and /*!40000 ALTER TABLE tbl_name ENABLE KEYS */; statements. This makes loading the dump file faster because the indexes are created after all rows are inserted. This option is effective only for nonunique indexes of MyISAM tables.

  • --dump-date

    If the --comments option is given, mysqldump produces a comment at the end of the dump of the following form:

    -- Dump completed on DATE
    

    However, the date causes dump files taken at different times to appear to be different, even if the data are otherwise identical. --dump-date and --skip-dump-date control whether the date is added to the comment. The default is --dump-date (include the date in the comment). --skip-dump-date suppresses date printing.

  • --dump-slave[=value]

    This option is similar to --master-data except that it is used to dump a replication slave server to produce a dump file that can be used to set up another server as a slave that has the same master as the dumped server. It causes the dump output to include a CHANGE MASTER TO statement that indicates the binary log coordinates (file name and position) of the dumped slave's master (rather than the coordinates of the dumped server, as is done by the --master-data option). These are the master server coordinates from which the slave should start replicating. This option was added in MySQL 5.5.3.

    The option value is handled the same way as for --master-data and has the same effect as --master-data in terms of enabling or disabling other options and in how locking is handled.

    In conjunction with --dump-slave, the --apply-slave-statements and --include-master-host-port options can also be used.

  • --events, -E

    Include Event Scheduler events for the dumped databases in the output.

  • --extended-insert, -e

    Use multiple-row INSERT syntax that include several VALUES lists. This results in a smaller dump file and speeds up inserts when the file is reloaded.

  • --fields-terminated-by=..., --fields-enclosed-by=..., --fields-optionally-enclosed-by=..., --fields-escaped-by=...

    These options are used with the --tab option and have the same meaning as the corresponding FIELDS clauses for LOAD DATA INFILE. See Section 12.2.6, “LOAD DATA INFILE Syntax”.

  • --first-slave

    Deprecated. Use --lock-all-tables instead. --first-slave was removed in MySQL 5.5.3.

  • --flush-logs, -F

    Flush the MySQL server log files before starting the dump. This option requires the RELOAD privilege. If you use this option in combination with the --all-databases option, the logs are flushed for each database dumped. The exception is when using --lock-all-tables 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.

  • --host=host_name, -h host_name

    Dump data from the MySQL server on the given host. The default host is localhost.

  • --hex-blob

    Dump binary columns using hexadecimal notation (for example, 'abc' becomes 0x616263). The affected data types are BINARY, VARBINARY, the BLOB types, and BIT.

  • --include-master-host-port

    For the CHANGE MASTER TO statement in a slave dump produced with the --dump-slave option, add MASTER_PORT and MASTER_PORT options for the host name and TCP/IP port number of the slave's master. This option was added in MySQL 5.5.3.

  • --ignore-table=db_name.tbl_name

    Do not dump the given table, which must be specified using both the database and table names. To ignore multiple tables, use this option multiple times. This option also can be used to ignore views.

  • --insert-ignore

    Write INSERT IGNORE statements rather than INSERT statements.

  • --lines-terminated-by=...

    This option is used with the --tab option and has the same meaning as the corresponding LINES clause for LOAD DATA INFILE. See Section 12.2.6, “LOAD DATA INFILE Syntax”.

  • --lock-all-tables, -x

    Lock all tables across all databases. This is achieved by acquiring a global read lock for the duration of the whole dump. This option automatically turns off --single-transaction and --lock-tables.

  • --lock-tables, -l

    For each dumped database, lock all tables to be dumped before dumping them. The tables are locked with READ LOCAL to permit concurrent inserts in the case of MyISAM tables. For transactional tables such as InnoDB, --single-transaction is a much better option than --lock-tables because it does not need to lock the tables at all.

    Because --lock-tables locks tables for each database separately, this option does not guarantee that the tables in the dump file are logically consistent between databases. Tables in different databases may be dumped in completely different states.

  • --log-error=file_name

    Log warnings and errors by appending them to the named file. The default is to do no logging.

  • --master-data[=value]

    Use this option to dump a master replication server to produce a dump file that can be used to set up another server as a slave of the master. It causes the dump output to include a CHANGE MASTER TO statement that indicates the binary log coordinates (file name and position) of the dumped server. These are the master server coordinates from which the slave should start replicating after you load the dump file into the slave.

    If the option value is 2, the CHANGE MASTER TO statement is written as an SQL comment, and thus is informative only; it has no effect when the dump file is reloaded. If the option value is 1, the statement is not written as a comment and takes effect when the dump file is reloaded. If no option value is specified, the default value is 1.

    This option requires the RELOAD privilege and the binary log must be enabled.

    The --master-data option automatically turns off --lock-tables. It also turns on --lock-all-tables, unless --single-transaction also is specified, in which case, a global read lock is acquired only for a short time at the beginning of the dump (see the description for --single-transaction). In all cases, any action on logs happens at the exact moment of the dump.

    It is also possible to set up a slave by dumping an existing slave of the master. 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.

  • --no-autocommit

    Enclose the INSERT statements for each dumped table within SET autocommit = 0 and COMMIT statements.

  • --no-create-db, -n

    This option suppresses the CREATE DATABASE statements that are otherwise included in the output if the --databases or --all-databases option is given.

  • --no-create-info, -t

    Do not write CREATE TABLE statements that re-create each dumped table.

    Note

    This option does not not exclude statements creating log file groups or tablespaces from mysqldump output; however, you can use the --no-tablespaces option for this purpose.

  • --no-data, -d

    Do not write any table row information (that is, do not dump table contents). This is useful if you want to dump only the CREATE TABLE statement for the table (for example, to create an empty copy of the table by loading the dump file).

  • --no-set-names, -N

    This has the same effect as --skip-set-charset.

  • --no-tablespaces, -y

    This option suppresses all CREATE LOGFILE GROUP and CREATE TABLESPACE statements in the output of mysqldump.

  • --opt

    This option is shorthand. It is the same as specifying --add-drop-table --add-locks --create-options --disable-keys --extended-insert --lock-tables --quick --set-charset. It should give you a fast dump operation and produce a dump file that can be reloaded into a MySQL server quickly.

    The --opt option is enabled by default. Use --skip-opt to disable it. See the discussion at the beginning of this section for information about selectively enabling or disabling a subset of the options affected by --opt.

  • --order-by-primary

    Dump each table's rows sorted by its primary key, or by its first unique index, if such an index exists. This is useful when dumping a MyISAM table to be loaded into an InnoDB table, but will make the dump operation take considerably longer.

  • --password[=password], -p[password]

    The password to use when connecting to the server. If you use the short option form (-p), you cannot have a space between the option and the password. If you omit the password value following the --password or -p option on the command line, mysqldump prompts for one.

    Specifying a password on the command line should be considered insecure. See Section 5.3.2.2, “End-User Guidelines for Password Security”. You can use an option file to avoid giving the password on the command line.

  • --pipe, -W

    On Windows, connect to the server using a named pipe. This option applies only if the server supports named-pipe connections.

  • --plugin-dir=path

    The directory in which to look for plugins. It may be necessary to specify this option if the --default-auth option is used to specify an authentication plugin but mysql does not find it. See Section 5.5.6, “Pluggable Authentication”.

    This option was added in MySQL 5.5.9.

  • --port=port_num, -P port_num

    The TCP/IP port number to use for the connection.

  • --protocol={TCP|SOCKET|PIPE|MEMORY}

    The connection protocol to use for connecting to the server. It is useful when the other connection parameters normally would cause a protocol to be used other than the one you want. For details on the permissible values, see Section 4.2.2, “Connecting to the MySQL Server”.

  • --quick, -q

    This option is useful for dumping large tables. It forces mysqldump to retrieve rows for a table from the server a row at a time rather than retrieving the entire row set and buffering it in memory before writing it out.

  • --quote-names, -Q

    Quote identifiers (such as database, table, and column names) within “`” characters. If the ANSI_QUOTES SQL mode is enabled, identifiers are quoted within “"” characters. This option is enabled by default. It can be disabled with --skip-quote-names, but this option should be given after any option such as --compatible that may enable --quote-names.

  • --replace

    Write REPLACE statements rather than INSERT statements.

  • --result-file=file_name, -r file_name

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

  • --routines, -R

    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 MySQL 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-comments

    See the description for the --comments option.

  • --skip-opt

    See the description for the --opt option.

  • --socket=path, -S path

    For connections to localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.

  • --ssl*

    Options that begin with --ssl specify whether to connect to the server using SSL and indicate where to find SSL keys and certificates. See Section 5.5.8.3, “SSL Command Options”.

  • --tab=path, -T path

    Produce tab-separated text-format data files. For each dumped table, mysqldump creates a tbl_name.sql file that contains the CREATE TABLE statement that creates the table, and the server writes a tbl_name.txt file that contains its data. The option value is the directory in which to write the files.

    Note

    This option should be used only when mysqldump is run on the same machine as the mysqld server. You must have the FILE privilege, and the server must have permission to write files in the directory that you specify.

    By default, the .txt data files are formatted using tab characters between column values and a newline at the end of each line. The format can be specified explicitly using the --fields-xxx and --lines-terminated-by options.

    Column values are converted to the character set specified by the --default-character-set option.

  • --tables

    Override the --databases or -B option. mysqldump regards all name arguments following the option as table names.

  • --triggers

    Include triggers for each dumped table in the output. This option is enabled by default; disable it with --skip-triggers.

  • --tz-utc

    This option enables TIMESTAMP columns to be dumped and reloaded between servers in different time zones. mysqldump sets its connection time zone to UTC and adds SET TIME_ZONE='+00:00' to the dump file. Without this option, TIMESTAMP columns are dumped and reloaded in the time zones local to the source and destination servers, which can cause the values to change if the servers are in different time zones. --tz-utc also protects against changes due to daylight saving time. --tz-utc is enabled by default. To disable it, use --skip-tz-utc.

  • --user=user_name, -u user_name

    The MySQL user name to use when connecting to the server.

  • --verbose, -v

    Verbose mode. Print more information about what the program does.

  • --version, -V

    Display version information and exit.

  • --where='where_condition', -w 'where_condition'

    Dump only rows selected by the given WHERE condition. Quotes around the condition are mandatory if it contains spaces or other characters that are special to your command interpreter.

    Examples:

    --where="user='jimf'"
    -w"userid>1"
    -w"userid<1"
    
  • --xml, -X

    Write dump output as well-formed XML.

    NULL, 'NULL', and Empty Values: For a column named column_name, the NULL value, an empty string, and the string value 'NULL' are distinguished from one another in the output generated by this option as follows.

    Value:XML Representation:
    NULL (unknown value)

    <field name="column_name" xsi:nil="true" />

    '' (empty string)

    <field name="column_name"></field>

    'NULL' (string value)

    <field name="column_name">NULL</field>

    The output from the mysql client when run using the --xml option also follows the preceding rules. (See Section 4.5.1.1, “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 MySQL 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 MySQL server to another:

shell> mysqldump --opt db_name | mysql --host=remote_host -C db_name

It is possible to dump several databases with one command:

shell> mysqldump --databases db_name1 [db_name2 ...] > my_databases.sql

To dump all databases, use the --all-databases option:

shell> mysqldump --all-databases > all_databases.sql

For InnoDB tables, mysqldump provides a way of making an online backup:

shell> mysqldump --all-databases --single-transaction > all_databases.sql

This backup acquires a global read lock on all tables (using FLUSH TABLES WITH READ LOCK) at the beginning of the dump. As soon as this lock has been acquired, the binary log coordinates are read and the lock is released. If long updating statements are running when the FLUSH statement is issued, the MySQL server may get stalled until those statements finish. After that, the dump becomes lock free and does not disturb reads and writes on the tables. If the update statements that the MySQL server receives are short (in terms of execution time), the initial lock period should not be noticeable, even with many updates.

For point-in-time recovery (also known as “roll-forward,” when you need to restore an old backup and replay the changes that happened since that backup), it is often useful to rotate the binary log (see Section 5.2.4, “The Binary Log”) or at least know the binary log coordinates to which the dump corresponds:

shell> mysqldump --all-databases --master-data=2 > all_databases.sql

Or:

shell> mysqldump --all-databases --flush-logs --master-data=2
              > all_databases.sql

The --master-data and --single-transaction options can be used simultaneously, which provides a convenient way to make an online backup suitable for use prior to point-in-time recovery if tables are stored using the InnoDB storage engine.

For more information on making backups, see Section 6.2, “Database Backup Methods”, and Section 6.3, “Example Backup and Recovery Strategy”.

If you encounter problems backing up views, please read the section that covers restrictions on views which describes a workaround for backing up views when this fails due to insufficient privileges. See Section E.5, “Restrictions on Views”.

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