Follow Techotopia on Twitter

On-line Guides
All Guides
eBook Store
iOS / Android
Linux for Beginners
Office Productivity
Linux Installation
Linux Security
Linux Utilities
Linux Virtualization
Linux Kernel
System/Network Admin
Programming
Scripting Languages
Development Tools
Web Development
GUI Toolkits/Desktop
Databases
Mail Systems
openSolaris
Eclipse Documentation
Techotopia.com
Virtuatopia.com

How To Guides
Virtualization
General System Admin
Linux Security
Linux Filesystems
Web Servers
Graphics & Desktop
PC Hardware
Windows
Problem Solutions

  




 

 

6.9. Replication Startup Options

This section describes the options that you can use on slave replication servers. You can specify these options either on the command line or in an option file.

On the master and each slave, you must use the server-id option to establish a unique replication ID. For each server, you should pick a unique positive integer in the range from 1 to 232 – 1, and each ID must be different from every other ID. Example: server-id=3

Options that you can use on the master server for controlling binary logging are described in Section 5.11.4, “The Binary Log”.

Some slave server replication options are handled in a special way, in the sense that each is ignored if a master.info file exists when the slave starts and contains a value for the option. The following options are handled this way:

  • --master-host

  • --master-user

  • --master-password

  • --master-port

  • --master-connect-retry

  • --master-ssl

  • --master-ssl-ca

  • --master-ssl-capath

  • --master-ssl-cert

  • --master-ssl-cipher

  • --master-ssl-key

The master.info file format in MySQL 5.1 includes values corresponding to the SSL options. In addition, the file format includes as its first line the number of lines in the file. If you upgrade an older server (before MySQL 4.1.1) to a newer version, the new server upgrades the master.info file to the new format automatically when it starts. However, if you downgrade a newer server to an older version, you should remove the first line manually before starting the older server for the first time.

If no master.info file exists when the slave server starts, it uses the values for those options that are specified in option files or on the command line. This occurs when you start the server as a replication slave for the very first time, or when you have run RESET SLAVE and then have shut down and restarted the slave.

If the master.info file exists when the slave server starts, the server uses its contents and ignores any options that correspond to the values listed in the file. Thus, if you start the slave server with different values of the startup options that correspond to values in the master.info file, the different values have no effect, because the server continues to use the master.info file. To use different values, you must either restart after removing the master.info file or (preferably) use the CHANGE MASTER TO statement to reset the values while the slave is running.

Suppose that you specify this option in your my.cnf file:

[mysqld]
master-host=some_host

The first time you start the server as a replication slave, it reads and uses that option from the my.cnf file. The server then records the value in the master.info file. The next time you start the server, it reads the master host value from the master.info file only and ignores the value in the option file. If you modify the my.cnf file to specify a different master host of some_other_host, the change still has no effect. You should use CHANGE MASTER TO instead.

Because the server gives an existing master.info file precedence over the startup options just described, you might prefer not to use startup options for these values at all, and instead specify them by using the CHANGE MASTER TO statement. See Section 13.6.2.1, “CHANGE MASTER TO Syntax”.

This example shows a more extensive use of startup options to configure a slave server:

[mysqld]
server-id=2
master-host=db-master.mycompany.com
master-port=3306
master-user=pertinax
master-password=freitag
master-connect-retry=60
report-host=db-slave.mycompany.com

The following list describes startup options for controlling replication. Many of these options can be reset while the server is running by using the CHANGE MASTER TO statement. Others, such as the --replicate-* options, can be set only when the slave server starts.

  • --log-slave-updates

    Normally, a slave does not log to its own binary log any updates that are received from a master server. This option tells the slave to log the updates performed by its SQL thread to its own binary log. For this option to have any effect, the slave must also be started with the --log-bin option to enable binary logging. --log-slave-updates is used when you want to chain replication servers. For example, you might want to set up replication servers using this arrangement:

    A -> B -> C
    

    Here, A serves as the master for the slave B, and B serves as the master for the slave C. For this to work, B must be both a master and a slave. You must start both A and B with --log-bin to enable binary logging, and B with the --log-slave-updates option so that updates received from A are logged by B to its binary log.

  • --log-warnings

    This option causes a server to print more messages to the error log about what it is doing. With respect to replication, the server generates warnings that it succeeded in reconnecting after a network/connection failure, and informs you as to how each slave thread started. This option is enabled by default; to disable it, use --skip-log-warnings. Aborted connections are not logged to the error log unless the value is greater than 1.

  • --master-connect-retry=seconds

    The number of seconds that the slave thread sleeps before trying to reconnect to the master in case the master goes down or the connection is lost. The value in the master.info file takes precedence if it can be read. If not set, the default is 60.

  • --master-host=host_name

    The hostname or IP number of the master replication server. The value in master.info takes precedence if it can be read. If no master host is specified, the slave thread does not start.

  • --master-info-file=file_name

    The name to use for the file in which the slave records information about the master. The default name is mysql.info in the data directory.

  • --master-password=password

    The password of the account that the slave thread uses for authentication when it connects to the master. The value in the master.info file takes precedence if it can be read. If not set, an empty password is assumed.

  • --master-port=port_number

    The TCP/IP port number that the master is listening on. The value in the master.info file takes precedence if it can be read. If not set, the compiled-in setting is assumed (normally 3306).

  • --master-retry-count=count

    The number of times that the slave tries to connect to the master before giving up.

  • --master-ssl, --master-ssl-ca=file_name, --master-ssl-capath=directory_name, --master-ssl-cert=file_name, --master-ssl-cipher=cipher_list, --master-ssl-key=file_name

    These options are used for setting up a secure replication connection to the master server using SSL. Their meanings are the same as the corresponding --ssl, --ssl-ca, --ssl-capath, --ssl-cert, --ssl-cipher, --ssl-key options that are described in Section 5.8.7.5, “SSL Command Options”. The values in the master.info file take precedence if they can be read.

  • --master-user=user_name

    The username of the account that the slave thread uses for authentication when it connects to the master. This account must have the REPLICATION SLAVE privilege. The value in the master.info file, if it can be read, takes precedence. If the master username is not set, the name test is assumed.

  • --max-relay-log-size=size

    The size at which the server rotates relay log files automatically. For more information, see Section 6.4.4, “Replication Relay and Status Files”.

  • --read-only

    Cause the slave to allow no updates except from slave threads or from users having the SUPER privilege. This enables you to ensure that a slave server accepts no updates from clients. This option does not apply to TEMPORARY tables.

  • --relay-log=file_name

    The name for the relay log. The default name is host_name-relay-bin.nnnnnn, where host_name is the name of the slave server host and nnnnnn indicates that relay logs are created in numbered sequence. You can specify the option to create hostname-independent relay log names, or if your relay logs tend to be big (and you don't want to decrease max_relay_log_size) and you need to put them in some area different from the data directory, or if you want to increase speed by balancing load between disks.

  • --relay-log-index=file_name

    The name to use for the relay log index file. The default name is host_name-relay-bin.index in the data directory, where host_name is the name of the slave server.

  • --relay-log-info-file=file_name

    The name to use for the file in which the slave records information about the relay logs. The default name is relay-log.info in the data directory.

  • --relay-log-purge={0|1}

    Disable or enable automatic purging of relay logs as soon as they are not needed any more. The default value is 1 (enabled). This is a global variable that can be changed dynamically with SET GLOBAL relay_log_purge = N.

  • --relay-log-space-limit=size

    This option places an upper limit on the total size in bytes of all relay logs on the slave. A value of 0 means “no limit.” This is useful for a slave server host that has limited disk space. When the limit is reached, the I/O thread stops reading binary log events from the master server until the SQL thread has caught up and deleted some unused relay logs. Note that this limit is not absolute: There are cases where the SQL thread needs more events before it can delete relay logs. In that case, the I/O thread exceeds the limit until it becomes possible for the SQL thread to delete some relay logs, because not doing so would cause a deadlock. You should not set --relay-log-space-limit to less than twice the value of --max-relay-log-size (or --max-binlog-size if --max-relay-log-size is 0). In that case, there is a chance that the I/O thread waits for free space because --relay-log-space-limit is exceeded, but the SQL thread has no relay log to purge and is unable to satisfy the I/O thread. This forces the I/O thread to temporarily ignore --relay-log-space-limit.

  • --replicate-do-db=db_name

    Tell the slave to restrict replication to statements where the default database (that is, the one selected by USE) is db_name. To specify more than one database, use this option multiple times, once for each database. Note that this does not replicate cross-database statements such as UPDATE some_db.some_table SET foo='bar' while having selected a different database or no database.

    An example of what does not work as you might expect: If the slave is started with --replicate-do-db=sales and you issue the following statements on the master, the UPDATE statement is not replicated:

    USE prices;
    UPDATE sales.january SET amount=amount+1000;
    

    The main reason for this “just check the default database” behavior is that it is difficult from the statement alone to know whether it should be replicated (for example, if you are using multiple-table DELETE statements or multiple-table UPDATE statements that act across multiple databases). It is also faster to check only the default database rather than all databases if there is no need.

    If you need cross-database updates to work, use --replicate-wild-do-table=db_name.% instead. See Section 6.10, “How Servers Evaluate Replication Rules”.

  • --replicate-do-table=db_name.tbl_name

    Tell the slave thread to restrict replication to the specified table. To specify more than one table, use this option multiple times, once for each table. This works for cross-database updates, in contrast to --replicate-do-db. See Section 6.10, “How Servers Evaluate Replication Rules”.

  • --replicate-ignore-db=db_name

    Tells the slave to not replicate any statement where the default database (that is, the one selected by USE) is db_name. To specify more than one database to ignore, use this option multiple times, once for each database. You should not use this option if you are using cross-database updates and you do not want these updates to be replicated. See Section 6.10, “How Servers Evaluate Replication Rules”.

    An example of what does not work as you might expect: If the slave is started with --replicate-ignore-db=sales and you issue the following statements on the master, the UPDATE statement is not replicated:

    USE prices;
    UPDATE sales.january SET amount=amount+1000;
    

    If you need cross-database updates to work, use --replicate-wild-ignore-table=db_name.% instead. See Section 6.10, “How Servers Evaluate Replication Rules”.

  • --replicate-ignore-table=db_name.tbl_name

    Tells the slave thread to not replicate any statement that updates the specified table, even if any other tables might be updated by the same statement. To specify more than one table to ignore, use this option multiple times, once for each table. This works for cross-database updates, in contrast to --replicate-ignore-db. See Section 6.10, “How Servers Evaluate Replication Rules”.

  • --replicate-rewrite-db=from_name->to_name

    Tells the slave to translate the default database (that is, the one selected by USE) to to_name if it was from_name on the master. Only statements involving tables are affected (not statements such as CREATE DATABASE, DROP DATABASE, and ALTER DATABASE), and only if from_name is the default database on the master. This does not work for cross-database updates. The database name translation is done before the --replicate-* rules are tested.

    If you use this option on the command line and the ‘>’ character is special to your command interpreter, quote the option value. For example:

    shell> mysqld --replicate-rewrite-db="olddb->newdb"
    
  • --replicate-same-server-id

    To be used on slave servers. Usually you should use the default setting of 0, to prevent infinite loops caused by circular replication. If set to 1, the slave does not skip events having its own server ID. Normally, this is useful only in rare configurations. Cannot be set to 1 if --log-slave-updates is used. Note that by default the slave I/O thread does not even write binary log events to the relay log if they have the slave's server id (this optimization helps save disk usage). So if you want to use --replicate-same-server-id, be sure to start the slave with this option before you make the slave read its own events that you want the slave SQL thread to execute.

  • --replicate-wild-do-table=db_name.tbl_name

    Tells the slave thread to restrict replication to statements where any of the updated tables match the specified database and table name patterns. Patterns can contain the ‘%’ and ‘_’ wildcard characters, which have the same meaning as for the LIKE pattern-matching operator. To specify more than one table, use this option multiple times, once for each table. This works for cross-database updates. See Section 6.10, “How Servers Evaluate Replication Rules”.

    Example: --replicate-wild-do-table=foo%.bar% replicates only updates that use a table where the database name starts with foo and the table name starts with bar.

    If the table name pattern is %, it matches any table name and the option also applies to database-level statements (CREATE DATABASE, DROP DATABASE, and ALTER DATABASE). For example, if you use --replicate-wild-do-table=foo%.%, database-level statements are replicated if the database name matches the pattern foo%.

    To include literal wildcard characters in the database or table name patterns, escape them with a backslash. For example, to replicate all tables of a database that is named my_own%db, but not replicate tables from the my1ownAABCdb database, you should escape the ‘_’ and ‘%’ characters like this: --replicate-wild-do-table=my\_own\%db. If you're using the option on the command line, you might need to double the backslashes or quote the option value, depending on your command interpreter. For example, with the bash shell, you would need to type --replicate-wild-do-table=my\\_own\\%db.

  • --replicate-wild-ignore-table=db_name.tbl_name

    Tells the slave thread not to replicate a statement where any table matches the given wildcard pattern. To specify more than one table to ignore, use this option multiple times, once for each table. This works for cross-database updates. See Section 6.10, “How Servers Evaluate Replication Rules”.

    Example: --replicate-wild-ignore-table=foo%.bar% does not replicate updates that use a table where the database name starts with foo and the table name starts with bar.

    For information about how matching works, see the description of the --replicate-wild-do-table option. The rules for including literal wildcard characters in the option value are the same as for --replicate-wild-ignore-table as well.

  • --report-host=slave_name

    The hostname or IP number of the slave to be reported to the master during slave registration. This value appears in the output of SHOW SLAVE HOSTS on the master server. Leave the value unset if you do not want the slave to register itself with the master. Note that it is not sufficient for the master to simply read the IP number of the slave from the TCP/IP socket after the slave connects. Due to NAT and other routing issues, that IP may not be valid for connecting to the slave from the master or other hosts.

  • --report-port=slave_port_num

    The TCP/IP port number for connecting to the slave, to be reported to the master during slave registration. Set this only if the slave is listening on a non-default port or if you have a special tunnel from the master or other clients to the slave. If you are not sure, do not use this option.

  • --skip-slave-start

    Tells the slave server not to start the slave threads when the server starts. To start the threads later, use a START SLAVE statement.

  • --slave_compressed_protocol={0|1}

    If this option is set to 1, use compression for the slave/master protocol if both the slave and the master support it.

  • --slave-load-tmpdir=file_name

    The name of the directory where the slave creates temporary files. This option is by default equal to the value of the tmpdir system variable. When the slave SQL thread replicates a LOAD DATA INFILE statement, it extracts the file to be loaded from the relay log into temporary files, and then loads these into the table. If the file loaded on the master is huge, the temporary files on the slave are huge, too. Therefore, it might be advisable to use this option to tell the slave to put temporary files in a directory located in some filesystem that has a lot of available space. In that case, the relay logs are huge as well, so you might also want to use the --relay-log option to place the relay logs in that filesystem.

    The directory specified by this option should be located in a disk-based filesystem (not a memory-based filesystem) because the temporary files used to replicate LOAD DATA INFILE must survive machine restarts. The directory also should not be one that is cleared by the operating system during the system startup process.

  • --slave-net-timeout=seconds

    The number of seconds to wait for more data from the master before the slave considers the connection broken, aborts the read, and tries to reconnect. The first retry occurs immediately after the timeout. The interval between retries is controlled by the --master-connect-retry option.

  • --slave-skip-errors=[err_code1,err_code2,...|all]

    Normally, replication stops when an error occurs on the slave. This gives you the opportunity to resolve the inconsistency in the data manually. This option tells the slave SQL thread to continue replication when a statement returns any of the errors listed in the option value.

    Do not use this option unless you fully understand why you are getting errors. If there are no bugs in your replication setup and client programs, and no bugs in MySQL itself, an error that stops replication should never occur. Indiscriminate use of this option results in slaves becoming hopelessly out of synchrony with the master, with you having no idea why this has occurred.

    For error codes, you should use the numbers provided by the error message in your slave error log and in the output of SHOW SLAVE STATUS. Appendix B, Error Codes and Messages, lists server error codes.

    You can also (but should not) use the very non-recommended value of all to cause the slave to ignore all error messages and keeps going regardless of what happens. Needless to say, if you use all, there are no guarantees regarding the integrity of your data. Please do not complain (or file bug reports) in this case if the slave's data is not anywhere close to what it is on the master. You have been warned.

    Examples:

    --slave-skip-errors=1062,1053
    --slave-skip-errors=all
    

 
 
  Published under the terms of the GNU General Public License Design by Interspire