Configure MariaDB Xpand as a Replication Master


When outbound replication is used with MariaDB Xpand, the master Xpand cluster must be configured to maintain binary logs.


  • MariaDB Xpand 5.3

  • MariaDB Xpand 6.0

  • MariaDB Xpand 6.1

About Binary Logs

Xpand implements MySQL compatible binlogs that with the following additional features:

  • Xpand can maintain multiple independent binary logs (for example, binlogs per table, per database, or for a set of tables and databases).

  • The binary logs are fault-tolerant, with the same guarantees as the rest of the Xpand system.

  • Writes to the binlog are transactional, consistent, and durable (full ACID guarantee).

  • Binary logs can be created and dropped online.

To configure a Xpand system with a single row-based binary log, issue the following commands:

master> CREATE BINLOG 'clustrix-bin' FORMAT='ROW';

To disable binary logging and drop (permanently) an existing binlog:

master> DROP BINLOG 'clustrix-bin';


When running MySQL database as a slave to a Xpand master, Xpand does not support the variable binlog_checksum, which causes the master to write checksums for events written to the binary log.

Create Replication User

The user name and password used for replication are stored as plain text within the binlogs. As such, Xpand recommends establishing a separate account for exclusive use with replication to prevent compromising the security of regularly used accounts.

Follow this sample to create an account that will be used when setting up a slave. You must have privileges to CREATE USER and GRANT to perform this step.

master> CREATE USER 'replication'@'%' IDENTIFIED BY 'clustrix';
master> GRANT REPLICATION SLAVE ON *.* TO 'replication'@'%';

Creating a Binary Log File

To create a binary log, issue the following command:


master> CREATE BINLOG 'binlog_name' [LOG (target1, target2, ...),] [IGNORE (target3, target4, ...),] [FORMAT='STATEMENT'|'ROW']


master> CREATE BINLOG 'mybinlog' FORMAT='ROW';

Optional attributes are:

  • LOG: A list of specific tables or databases to log

  • IGNORE: A list of specific tables or databases to ignore

  • FORMAT: Format specifier (STATEMENT or ROW default is ROW).

By default, this command creates a binary log file for the entire cluster in ROW format. Alternatively, you can create binlogs that scope a database or a list of tables. For more information, please see the section on Configure Binlog Scope with MariaDB Xpand.

For most workloads, row-based replication (FORMAT ='ROW') provides better performance than statement-based replication (FORMAT ='STATEMENT'). If you are unsure what is most appropriate for your environment, contact MariaDB Support.


If a database is set to both LOG and IGNORE, Xpand will IGNORE. This deviates from MySQL, which will log and not ignore.

Setting Binary Logging Options

To configure binary logging options, issue the ALTER BINLOG command. Options for the ALTER BINLOG logfile command are as follows.



LOG (db1, db2)

Only log updates to databases db1 and db2

IGNORE (db3)

Ignore updates to db3

ADD LOG (db4)

Log updates to db4, in addition to others


Ignore updates to db5, in addition to others

DROP LOG (db6)

Stop logging to db6


Log updates to all databases, as opposed to specific databases. Does not reset the IGNORE list.


Disable logging to this binlog


Enable logging to this binlog


Rename specified binlog to "bar"

FORMAT='row' or 'statement'

Configure log format (row-based or statement-based)

Displaying Binary Log Information

If only one binary log exists, you can display its filename, segment number and position by issuing the following command:


If more than one binary log exists, the log configured by the global variable master_status_binlog is displayed. If master_status_binlog is unset, an error is returned. This behavior is compatible with behavior of the MySQL mysqldump --master-data command.

master> SET GLOBAL master_status_binlog = 'foo';

To display status for all binary logs, issue the following command:


To display detailed information about binary logs, issue the following command:


Most of this information is not directly useful, though log size can help you decide whether to trim the log.

Trimming a Binary Log

You can trim a binary log using either of the following methods:

  • TRIM BINLOG command

  • trim-binlog script

Trimming using the TRIM BINLOG Command

Back up your database regularly using the mysqldump --master-data command, which records the binary log filename at the start of the dump. To keep the size of the binary log under control, use this value to trim older data after it is backed up. The extent to which you trim is a matter of policy: you can choose to retain a week's history, or you might prefer to minimize disk consumption as much as possible by trimming all but the current file. To minimize the amount of space being used by your binary log, trim according to the Slave that is farthest behind in replication.

To list the files that compose the binary log, issue the following:

| File            | Size      | First Event Timestamp |
| eukanuba.000001 | 104857600 | 2016-01-09 19:51:08   |
| eukanuba.000002 | 104857600 | 2016-01-09 20:02:09   |
| eukanuba.000003 | 104857600 | 2016-01-09 22:22:27   |
| eukanuba.000004 | 104857600 | 2016-01-09 22:30:37   |
| eukanuba.000005 | 104857600 | 2016-01-09 22:38:11   |
| eukanuba.000006 | 104857600 | 2016-01-09 22:45:44   |
| eukanuba.000007 | 104857600 | 2016-01-09 22:53:03   |
| eukanuba.000008 | 104857600 | 2016-01-09 23:00:44   |
| eukanuba.000009 | 104857600 | 2016-01-09 23:07:46   |
| eukanuba.000010 | 104857600 | 2016-01-09 23:15:00   |

To display current Slave locations, issue the SHOW SLAVE STATUS command, which displays status as follows:

*************************** 1. row ***************************
            Slave_Name: default
          Slave_Status: Running
           Master_Host: alpo
           Master_Port: 3306
           Master_User: root
       Master_Log_File: alpo
         Slave_Enabled: Enabled
          Log_File_Seq: 3383
          Log_File_Pos: 58790712
            Last_Error: no error
     Connection_Status: Connected
  Relay_Log_Bytes_Read: 0
Relay_Log_Current_Size: 0
 Seconds_Behind_Master: 0
1 row in set (0.00 sec)

The filename argument is the filename returned by the SHOW MASTER STATUS command. The sequence number (Log_File_Seq) indicates the binary log file currently in use (it's the numeric portion of the file name). To delete old binary data without dropping the entire log, issue the following command (nnnnn represents the sequence number):

master> TRIM BINLOG 'binlog_name' BEFORE FILE 'binlog_name.nnnnn';

For example, if the clx001.000283 file is timestamped at 7:15 PM on September 28, 2016, the following sample would delete all log files before that time.

master> TRIM BINLOG 'clx001' BEFORE FILE 'clx001.000283';

Trimming Using the binlog-trim Script

You can find the binlog-trim script in /opt/clustrix/bin/binlog-trim of your system.


binlog-trim [options]




-h, --help

Show this help message and exit

-H HOST, --host=HOST

Specifies the host

-P PORT, --port=PORT

SQL port, default is mysql port: 3306

-u USER, --user=USER

Username, default is root

-p PASSWD, --passwd=PASSWD

Specifies the password

-n NUM_FILES, --num-files=NUM_FILES

Number of files to trim a time

-d, --dry

Do not perform any actual trims


Keep this many days of binlogs

-i INTERVAL, --interval=INTERVAL

Seconds between trims

-b BINLOG_NAME, --binlog_name=BINLOG_NAME

Name of binlog to trim; must specify if multiple binlogs exist

-M MAX_RUN_TIME_MINS, --max-run-time-mins=MAX_RUN_TIME_MINS

Maximum time (minutes) script may run

-V, --version

Indicates the version

binlog-trim is generally deployed as a cron job on one of the nodes. An example entry to run once a day at 5:35UTC, with a retention policy of 7 days, trimming no more than 50 files at a time, with a minimum 60-second pause between trims, and operating on the binlog called clustrix-bin:

35 5 * * * root /bin/binlog-trim -H localhost -i 60 -k 7 -n 50 -b clustrix-bin 2>&1 >> /var/log/binlog-trim.log


The INTERVAL is a minimum wait between trims; there is additional logic in the script to prevent the trims from building up too much cleanup work (the logs will indicate this with 'waiting for bigc to pass trim').

Backing Up Binary Logs

Because Xpand binary logs (binlogs) aren't stored as plain files, they cannot be backed up as MySQL binlogs can. For backup purposes, Xpand provides the repclient utility, which copies binlogs from a Xpand or MySQL system as if it were a replication slave. The repclient utility can be run on any Xpand node.

To copy all of the binlogs off a Xpand cluster, perform the following steps:

  1. To list the most recent binlog, issue the SHOW MASTER STATUS command. The command returns a filename such as clustrix-bin.001903.

  2. Create a directory in the /clustrix mount on a node and cd to it.

  3. To retrieve all binlog files up to the most recent, issue the following command:

    shell> node# repclient -addr -dumpbinlog -logname clustrix-bin.000001 -end_logname clustrix-bin.001903


By default, the tool outputs decoded binlog messages to stdout. To specify an output file, specify the -dumpbinlog option. If you intend to archive the binlogs, omit -logpos, which can create gaps in the resulting binlog. By default, the utility stays connected to the master. To specify when it is to disconnect, include the -end_logname or -end_logpos option.

Valid options for the repclient command are as follows:



-addr hostname

Database host (default:

-count n

Number of messages to dump


Dump binlog

-end_logname path

Ending replication log name

-end_logpos offset

Ending replication log position (default: EOF)


List command options


List command options plus debugging output options

-logname path

Starting replication log name

-logpos offset

Starting replication log position (default: 4)

-max-packet-size bytes

Maximum packet size (default: 16777216)

-max-retries n

Maximum retries after an error (default: 3)


Don't decode row values

-pass password

Database password (default: #undef)


Dump performance statistics

-perf-interval seconds

Dump performance statistics interval (default: 30)

-port port

Database port (default: 3306)

-retry-timeout seconds

Timeout in seconds for retries (default: 10)

-set-variable NAME= VALUE

Set a variable to the given value

-slave-id n

Slave ID (default: 1)


Test database connection and display status


Truncate any existing files

-user username

Database username (default: root)


Display debugging messages

Excluding A Session from Binary Logs

To prevent a session's statements from being written to any binary log, set sql_log_bin to false by executing SET:

SET sql_log_bin=false;

sql_log_bin is also available as a global variable.


Be careful using sql_log_bin in production. Improper use can lead to data skew between the master and the slave(s).

In MariaDB Xpand 6, you can also exclude a session from writing to specific binlogs using the sql_log_skip_binlogs system variable.

The sql_log_skip_binlogs system variable can be set at the session-level and accepts a comma-separated list of binlog names.

To exclude the current session's statements from binlogA and binlogB, set the system variable by executing SET:

SET sql_log_skip_binlogs='binlogA,binlogB';

To re-enable writes to all binlogs for the current session, set the system variable back to DEFAULT:

SET sql_log_skip_binlogs=DEFAULT;

Dropping a Binary Log File

To stop logging to the specified binary log and drop it from the system, issue the following command:

master> DROP BINLOG binlog_name;


You cannot recover a binary log after dropping it.

Global Variables

The following global and session variables control binary log behavior:



Default Value

Session Variable?


Always NONE. Xpand masters do not support generating event checksums.



Force all binlogs to log in this format, unless set to 'DEFAULT'.




Always OFF. Xpand masters do not support generating GTID events.



Dummy variable for compatibility. (Xpand does not support replication with Global Transaction Identifiers.)


Binlog used in SHOW MASTER STATUS when used without specifying a binlog.



Log statements to binary logs. This variable can be set to FALSE on a per-session basis.




Dummy variable for compatibility.



Exercise extreme care when changing these settings. The defaults may not be ideal for your system, but they should be reasonable. The product will not warn you if you configure inadvisable settings.