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.
mysqldump requires at least the
SELECT privilege for dumped
SHOW VIEW for dumped
SUPER for dumped triggers,
LOCK TABLES if the
--single-transaction 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
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:
Some mysqldump options are shorthand for groups of other options:
--optis the same as specifying
--set-charset. All of the options that
--optstands for also are on by default because
--optis on by default.
To reverse the effect of a group option, uses its
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
--optexcept for some features, use the
--skipoption for each feature. To disable extended inserts and memory buffering, use
--skip-quickis sufficient because
--optis on by default.)
When you selectively enable or disable the effect of a group
option, order is important because options are processed first
to last. For example,
--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
--opt option (and hence
--quick) is enabled by
default, so to enable memory buffering, use
Before MySQL 4.1.2, out-of-range numeric values such as
inf, as well as
NaN (not-a-number) values are dumped by
NULL. You can
see this using the following sample table:
CREATE TABLE t (f DOUBLE);mysql>
INSERT INTO t VALUES(1e+111111111111111111111);mysql>
INSERT INTO t VALUES(-1e111111111111111111111);mysql>
SELECT f FROM t;+------+ | f | +------+ | inf | | -inf | +------+
For this table, mysqldump produces the following data output:
-- -- Dumping data for table `t` -- INSERT INTO t VALUES (NULL); INSERT INTO t VALUES (NULL);
The significance of this behavior is that if you dump and
restore the table, the new table has contents that differ from
the original contents. This problem is fixed as of MySQL 4.1.2;
you cannot insert
inf in the table, so this
mysqldump behavior is only relevant when you
deal with old servers.
mysqldump supports the following options,
which can be specified on the command line or in the
groups of an option file. For information about option files
used by MySQL programs, see Section 4.2.6, “Using Option Files”.
|--add-drop-database||Add DROP DATABASE statement before each CREATE DATABASE statement|
|--add-drop-table||Add DROP TABLE statement before each CREATE TABLE statement|
|--add-locks||Surround each table dump with LOCK TABLES and UNLOCK TABLES statements|
|--all-databases||Dump all tables in all databases|
|--allow-keywords||Allow creation of column names that are keywords|
|--character-sets-dir||Directory where character sets are installed|
|--comments||Add comments to dump file|
|--compact||Produce more compact output|
|--compatible||Produce output that is more compatible with other database systems or with older MySQL servers|
|--complete-insert||Use complete INSERT statements that include column names|
|--compress||Compress all information sent between client and server|
|--create-options||Include all MySQL-specific table options in CREATE TABLE statements|
|--databases||Interpret all name arguments as database names|
|--debug||Write debugging log|
|--debug-info||Print debugging information, memory, and CPU statistics when program exits||5.0.32|
|--default-character-set||Specify default character set|
|--defaults-extra-file||Read named option file in addition to usual option files|
|--defaults-file||Read only named option file|
|--defaults-group-suffix||Option group suffix value||5.0.10|
|--delayed-insert||Write INSERT DELAYED statements rather than INSERT statements|
|--delete-master-logs||On a master replication server, delete the binary logs after performing the dump operation|
|--disable-keys||For each table, surround INSERT statements with statements to disable and enable keys|
|--dump-date||Include dump date as "Dump completed on" comment if --comments is given||5.0.52|
|--extended-insert||Use multiple-row INSERT syntax|
|--fields-enclosed-by||This option is used with the --tab option and has the same meaning as the corresponding clause for LOAD DATA INFILE|
|--fields-escaped-by||This option is used with the --tab option and has the same meaning as the corresponding clause for LOAD DATA INFILE|
|--fields-optionally-enclosed-by||This option is used with the --tab option and has the same meaning as the corresponding clause for LOAD DATA INFILE|
|--first-slave||Deprecated; use --lock-all-tables instead|
|--flush-logs||Flush MySQL server log files before starting dump|
|--flush-privileges||Emit a FLUSH PRIVILEGES statement after dumping mysql database|
|--force||Continue even if an SQL error occurs during a table dump|
|--help||Display help message and exit|
|--hex-blob||Dump binary columns using hexadecimal notation|
|--host||Host to connect to (IP address or hostname)|
|--ignore-table||Do not dump given table|
|--insert-ignore||Write INSERT IGNORE rather than INSERT statements|
|--lock-all-tables||Lock all tables across all databases|
|--lock-tables||Lock all tables before dumping them|
|--log-error||Append warnings and errors to named file||5.0.42|
|--master-data||Write the binary log file name and position to the output|
|--max_allowed_packet||Maximum packet length to send to or receive from server|
|--net_buffer_length||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||Do not write CREATE DATABASE statements|
|--no-create-info||Do not write CREATE TABLE statements that re-create each dumped table|
|--no-data||Do not dump table contents|
|--no-defaults||Read no option files|
|--no-set-names||Same as --skip-set-charset|
|--opt||Shorthand for --add-drop-table --add-locks --create-options --disable-keys --extended-insert --lock-tables --quick --set-charset.|
|--order-by-primary||Dump each table's rows sorted by its primary key, or by its first unique index|
|--password||Password to use when connecting to server|
|--pipe||On Windows, connect to server using named pipe|
|--port||TCP/IP port number to use for connection|
|--print-defaults||Print default options|
|--protocol||Connection protocol to use|
|--quick||Retrieve rows for a table from the server a row at a time|
|--quote-names||Quote identifiers within backtick characters|
|--result-file||Direct output to a given file|
|--routines||Dump stored routines (procedures and functions) from dumped databases||5.0.13|
|--set-charset||Add SET NAMES default_character_set to output|
|--shared-memory-base-name||The name of shared memory to use for shared-memory connections|
|--single-transaction||Issue a BEGIN SQL statement before dumping data from server|
|--skip-add-drop-table||Do not add a DROP TABLE statement before each CREATE TABLE statement|
|--skip-add-locks||Do not add locks|
|--skip-comments||Do not add comments to dump file|
|--skip-compact||Do not produce more compact output|
|--skip-disable-keys||Do not disable keys|
|--skip-extended-insert||Turn off extended-insert|
|--skip-opt||Turn off options set by --opt|
|--skip-quick||Do not retrieve rows for a table from the server a row at a time|
|--skip-quote-names||Do not quote identifiers|
|--skip-set-charset||Do not write SET NAMES statement|
|--skip-triggers||Do not dump triggers||5.0.11|
|--skip-tz-utc||Turn off tz-utc||5.0.15|
|--socket||For connections to localhost, the Unix socket file to use|
|--ssl||Enable SSL for connection|
|--ssl-ca||Path of file that contains list of trusted SSL CAs|
|--ssl-capath||Path of directory that contains trusted SSL CA certificates in PEM format|
|--ssl-cert||Path of file that contains X509 certificate in PEM format|
|--ssl-cipher||List of permitted ciphers to use for SSL encryption|
|--ssl-key||Path of file that contains X509 key in PEM format|
|--ssl-verify-server-cert||Verify Common Name value in server certificate against host name used when connecting to server||5.0.23|
|--tab||Produce tab-separated data files|
|--tables||Override --databases or -B option|
|--triggers||Dump triggers for each dumped table|
|--tz-utc||Add SET TIME_ZONE='+00:00' to dump file||5.0.15|
|--user||MySQL user name to use when connecting to server|
|--version||Display version information and exit|
|--where||Dump only rows selected by given WHERE condition|
|--xml||Produce XML output|
Display a help message and exit.
DROP DATABASEstatement before each
CREATE DATABASEstatement. This option is typically used in conjunction with the
--databasesoption because no
CREATE DATABASEstatements are written unless one of those options is specified.
Dump all tables in all databases. This is the same as using the
--databasesoption and naming all the databases on the command line.
Permit creation of column names that are keywords. This works by prefixing each column name with the table name.
The directory where character sets are installed. See Section 10.5, “Character Set Configuration”.
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
Prior to MySQL 5.0.48, this option did not create valid SQL if the database dump contained views. The recreation of views requires the creation and removal of temporary tables and this option suppressed the removal of those temporary tables. As a workaround, use
--add-drop-tableoption and then manually adjust the dump file.
Produce output that is more compatible with other database systems or with older MySQL servers. The value of
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=oracledoes 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.
INSERTstatements that include column names.
Compress all information sent between the client and the server if both support compression.
Include all MySQL-specific table options in the
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.
USEstatements are included in the output before each new database.
Write a debugging log. A typical
d:t:o,. The default value is
Print debugging information and memory and CPU usage statistics when the program exits. This option was added in MySQL 5.0.32.
This option has no effect for output data files produced by using the
--taboption. See the description for that option.
Read this option file after the global option file but (on Unix) before the user option file. As of MySQL 5.0.6, if the file does not exist or is otherwise inaccessible, an error occurs.
file_nameis the full path name to the file.
Use only the given option file. If the file does not exist or is otherwise inaccessible, an error occurs.
file_nameis the full path name to the file.
Read not only the usual option groups, but also groups with the usual names and a suffix of
str. For example, mysqldump normally reads the
[mysqldump]groups. If the
--defaults-group-suffix=_otheroption is given, mysqldump also reads the
[mysqldump_other]groups. This option was added in MySQL 5.0.10.
For each table, surround the
/*!40000 ALTER TABLEand
tbl_nameDISABLE KEYS */;
/*!40000 ALTER TABLEstatements. 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
tbl_nameENABLE KEYS */;
MyISAMtables. It has no effect for other tables.
-- Dump completed on
However, the date causes dump files taken at different times to appear to be different, even if the data are otherwise identical.
--skip-dump-datecontrol whether the date is added to the comment. The default is
--dump-date(include the date in the comment).
--skip-dump-datesuppresses date printing. This option was added in MySQL 5.0.52.
INSERTstatements using multiple-row syntax that includes several
VALUESlists. This results in a smaller dump file and speeds up inserts when the file is reloaded.
Flush the MySQL server log files before starting the dump. This option requires the
RELOADprivilege. If you use this option in combination with the
--all-databasesoption, the logs are flushed for each database dumped. The exception is when using
--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-logstogether with either
FLUSH PRIVILEGESstatement to the dump output after dumping the
mysqldatabase. This option should be used any time the dump contains the
mysqldatabase and any other database that depends on the data in the
mysqldatabase for proper restoration. This option was added in MySQL 5.0.26.
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.
Dump data from the MySQL server on the given host. The default host is
Dump binary columns using hexadecimal notation (for example,
0x616263). The affected data types are
VARBINARY, and the
BLOBtypes. As of MySQL 5.0.13,
BITcolumns are affected as well.
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.
For each dumped database, lock all tables to be dumped before dumping them. The tables are locked with
READ LOCALto permit concurrent inserts in the case of
MyISAMtables. For transactional tables such as
--single-transactionis a much better option than
--lock-tablesbecause it does not need to lock the tables at all.
--lock-tableslocks 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 warnings and errors by appending them to the named file. The default is to do no logging. This option was added in MySQL 5.0.42.
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 TOstatement 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 TOstatement 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
RELOADprivilege and the binary log must be enabled.
--master-dataoption automatically turns off
--lock-tables. It also turns on
--single-transactionalso 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:
Stop the slave's SQL thread and get its current status:
STOP SLAVE SQL_THREAD;mysql>
SHOW SLAVE STATUS;
From the output of the
SHOW SLAVE STATUSstatement, the binary log coordinates of the master server from which the new slave should start replicating are the values of the
Exec_Master_Log_Posfields. Denote those values as
Dump the slave server:
mysqldump --master-data=2 --all-databases > dumpfile
--master-data=2works only if binary logging has been enabled on the slave. Otherwise, mysqldump fails with the error Binlogging on server not active. In this case you must handle any locking issues in another manner, using one or more of
--single-transaction, as required by your application and environment.
Restart the slave:
On the new slave, load the dump file:
mysql < dumpfile
On the new slave, set the replication coordinates to those of the master server obtained earlier:
CHANGE MASTER TO->
MASTER_LOG_FILE = '
file_name', MASTER_LOG_POS =
CHANGE MASTER TOstatement might also need other parameters, such as
MASTER_HOSTto point the slave to the correct master server host. Add any such parameters as necessary.
Do not write
CREATE TABLEstatements that create each dumped table.
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 TABLEstatement for the table (for example, to create an empty copy of the table by loading the dump file).
Do not read any option files. If program startup fails due to reading unknown options from an option file,
--no-defaultscan be used to prevent them from being read.
This has the same effect as
This option is shorthand. It is the same as specifying
--set-charset. It should give you a fast dump operation and produce a dump file that can be reloaded into a MySQL server quickly.
--optoption is enabled by default. Use
--skip-optto 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
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
MyISAMtable to be loaded into an
InnoDBtable, but will make the dump operation take considerably longer.
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
passwordvalue following the
-poption on the command line, mysqldump prompts for one.
Specifying a password on the command line should be considered insecure. See Section 220.127.116.11, “End-User Guidelines for Password Security”. You can use an option file to avoid giving the password on the command line.
On Windows, connect to the server using a named pipe. This option applies only if the server supports named-pipe connections.
The TCP/IP port number to use for the connection.
Print the program name and all options that it gets from option files.
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”.
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 identifiers (such as database, table, and column names) within “
`” characters. If the
ANSI_QUOTESSQL 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
--compatiblethat may enable
Direct output to the named file. The result file is created and its previous contents overwritten, even if an error occurs while generating the dump.
This option should be used on Windows to prevent newline “
\n” characters from being converted to “
\r\n” carriage return/newline sequences.
Include stored routines (procedures and functions) for the dumped databases in the output. Use of this option requires the
SELECTprivilege for the
The output generated by using
CREATE FUNCTIONstatements to create the routines. However, these statements do not include attributes such as the routine creation and modification timestamps, so when the routines are reloaded, they are created with timestamps equal to the reload time.
If you require routines to be created with their original timestamp attributes, do not use
--routines. Instead, dump and reload the contents of the
mysql.proctable directly, using a MySQL account that has appropriate privileges for the
This option was added in MySQL 5.0.13. Before that, stored routines are not dumped. Routine
DEFINERvalues are not dumped until MySQL 5.0.20. This means that before 5.0.20, when routines are reloaded, they will be created with the definer set to the reloading user. If you require routines to be re-created with their original definer, dump and load the contents of the
mysql.proctable directly as described earlier.
SET NAMESto the output. This option is enabled by default. To suppress the
SET NAMESstatement, use
On Windows, the shared-memory name to use, for connections made using shared memory to a local server. The default value is
MYSQL. The shared-memory name is case sensitive.
The server must be started with the
--shared-memoryoption to enable shared-memory connections.
This option sets the transaction isolation mode to
REPEATABLE READand sends a
START TRANSACTIONSQL statement to the server before dumping data. It is useful only with transactional tables such as
BDB, because then it dumps the consistent state of the database at the time when
START TRANSACTIONwas issued without blocking any applications.
When using this option, you should keep in mind that only
InnoDBtables are dumped in a consistent state. For example, any
MEMORYtables dumped while using this option may still change state.
--single-transactiondump is in process, to ensure a valid dump file (correct table contents and binary log coordinates), no other connection should use the following statements:
TRUNCATE TABLE. A consistent read is not isolated from those statements, so use of them on a table to be dumped can cause the
SELECTthat is performed by mysqldump to retrieve the table contents to obtain incorrect contents or fail.
This option is not supported for MySQL Cluster tables; the results cannot be guaranteed to be consistent due to the fact that the
NDBCLUSTERstorage engine supports only the
READ_COMMITTEDtransaction isolation level. You should always use
NDBbackup and restore instead.
See the description for the
See the description for the
For connections to
localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.
Options that begin with
--sslspecify whether to connect to the server using SSL and indicate where to find SSL keys and certificates. See Section 18.104.22.168, “Command Options for Secure Connections”.
Produce tab-separated text-format data files. For each dumped table, mysqldump creates a
file that contains the
CREATE TABLEstatement that creates the table, and the server writes a
file that contains its data. The option value is the directory in which to write the files.
This option should be used only when mysqldump is run on the same machine as the mysqld server. Because the server creates files
*.txtfile in the directory that you specify, the directory must be writable by the server and the MySQL account that you use must have the
FILEprivilege. Because mysqldump creates
*.sqlin the same directory, it must be writable by your system login account.
By default, the
.txtdata 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
Column values are dumped using the
binarycharacter set and the
--default-character-setoption is ignored. In effect, there is no character set conversion. If a table contains columns in several character sets, the output data file will as well and you may not be able to reload the file correctly.
Include triggers for each dumped table in the output. This option is enabled by default; disable it with
--skip-triggers. This option was added in MySQL 5.0.11. Before that, triggers are not dumped.
This option enables
TIMESTAMPcolumns 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,
TIMESTAMPcolumns 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-utcalso protects against changes due to daylight saving time.
--tz-utcis enabled by default. To disable it, use
--skip-tz-utc. This option was added in MySQL 5.0.15.
The MySQL user name to use when connecting to the server.
Verbose mode. Print more information about what the program does.
Display version information and exit.
Dump only rows selected by the given
WHEREcondition. Quotes around the condition are mandatory if it contains spaces or other characters that are special to your command interpreter.
--where="user='jimf'" -w"userid>1" -w"userid<1"
Write dump output as well-formed XML.
'NULL', and Empty Values: For a column named
NULLvalue, 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:
column_name" xsi:nil="true" />
Beginning with MySQL 5.0.40, 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>
You can also set the following variables by using
The maximum size of the buffer for client/server communication. The default is 24MB, the maximum is 1GB.
The initial size of the buffer for client/server communication. When creating multiple-row
INSERTstatements (as with the
--optoption), mysqldump creates rows up to
net_buffer_lengthbytes long. If you increase this variable, ensure that the MySQL server
net_buffer_lengthsystem variable has a value at least this large.
It is also possible to set variables by using
--set-variable format is deprecated.
A common use of mysqldump is for making a backup of an entire database:
You can load the dump file back into the server like this:
Or like this:
mysql -e "source
mysqldump is also very useful for populating databases by copying data from one MySQL server to another:
db_name| mysql --host=
It is possible to dump several databases with one command:
db_name2...] > my_databases.sql
To dump all databases, use the
mysqldump --all-databases > all_databases.sql
mysqldump provides a way of making an online
mysqldump --all-databases --master-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
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 5.2.3, “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
mysqldump --all-databases --flush-logs --master-data=2
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 7.2, “Database Backup Methods”, and Section 7.3, “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 C.4, “Restrictions on Views”.