The Ultimate Guide to High Availability with MariaDB

START SLAVE

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The terms master and slave have historically been used in replication, and MariaDB has begun the process of adding primary and replica synonyms. The old terms will continue to be used to maintain backward compatibility - see MDEV-18777 to follow progress on this effort.

Syntax

START SLAVE ["connection_name"] [thread_type [, thread_type] ... ] [FOR CHANNEL "connection_name"]
START SLAVE ["connection_name"] [SQL_THREAD] UNTIL                
    MASTER_LOG_FILE = 'log_name', MASTER_LOG_POS = log_pos [FOR CHANNEL "connection_name"]
START SLAVE ["connection_name"] [SQL_THREAD] UNTIL
    RELAY_LOG_FILE = 'log_name', RELAY_LOG_POS = log_pos [FOR CHANNEL "connection_name"]
START SLAVE ["connection_name"] [SQL_THREAD] UNTIL
    MASTER_GTID_POS = <GTID position> [FOR CHANNEL "connection_name"]
START ALL SLAVES [thread_type [, thread_type]]

START REPLICA ["connection_name"] [thread_type [, thread_type] ... ] -- from 10.5.1
START REPLICA ["connection_name"] [SQL_THREAD] UNTIL                
    MASTER_LOG_FILE = 'log_name', MASTER_LOG_POS = log_pos -- from 10.5.1
START REPLICA ["connection_name"] [SQL_THREAD] UNTIL
    RELAY_LOG_FILE = 'log_name', RELAY_LOG_POS = log_pos -- from 10.5.1
START REPLICA ["connection_name"] [SQL_THREAD] UNTIL
    MASTER_GTID_POS = <GTID position> -- from 10.5.1
START ALL REPLICAS [thread_type [, thread_type]] -- from 10.5.1

thread_type: IO_THREAD | SQL_THREAD

Contents

  1. Syntax
  2. Description
    1. START SLAVE UNTIL
      1. SQL_BEFORE_GTIDS|SQL_AFTER_GTIDS
      2. connection_name
      3. START ALL SLAVES
      4. START REPLICA
  3. See Also

Description

START SLAVE (START REPLICA from MariaDB 10.5.1) with no thread_type options starts both of the replica threads (see replication) needed to connect with a master setup with CHANGE MASTER TO . The I/O thread reads events from the primary server and stores them in the relay log. The SQL thread reads events from the relay log and executes them. START SLAVE requires the SUPER privilege, or, from MariaDB 10.5.2, the REPLICATION SLAVE ADMIN privilege.

If START SLAVE succeeds in starting the replica threads, it returns without any error. However, even in that case, it might be that the replica threads start and then later stop (for example, because they do not manage to connect to the primary or read its binary log, or some other problem). START SLAVE does not warn you about this. You must check the replica's error log for error messages generated by the replica threads, or check that they are running satisfactorily with SHOW SLAVE STATUS (SHOW REPLICA STATUS from MariaDB 10.5.1).

START SLAVE UNTIL

START SLAVE UNTIL refers to the SQL_THREAD replica position at which the SQL_THREAD replication will halt. If SQL_THREAD isn't specified both threads are started.

START SLAVE UNTIL master_gtid_pos=xxx is also supported. See Global Transaction ID/START SLAVE UNTIL master_gtid_pos=xxx for more details.

MariaDB starting with 11.3.0
SQL_BEFORE_GTIDS|SQL_AFTER_GTIDS

MariaDB 11.3 extended the START SLAVE UNTIL command with the options SQL_BEFORE_GTIDS and SQL_AFTER_GTIDS to allow control of whether the replica stops before or after a provided GTID state. Its syntax is:

START SLAVE UNTIL (SQL_BEFORE_GTIDS|SQL_AFTER_GTIDS)="<gtid_list>"

See Global Transaction ID#SQL_BEFORE_GTIDS/SQL_AFTER_GTIDS for details.

connection_name

If there is only one nameless primary, or the default primary (as specified by the default_master_connection system variable) is intended, connection_name can be omitted. If provided, the START SLAVE statement will apply to the specified primary. connection_name is case-insensitive.

MariaDB starting with 10.7.0

The FOR CHANNEL keyword was added for MySQL compatibility. This is identical as using the channel_name directly after START SLAVE.

START ALL SLAVES

START ALL SLAVES starts all configured replicas (replicas with master_host not empty) that were not started before. It will give a note for all started connections. You can check the notes with SHOW WARNINGS.

START REPLICA

MariaDB starting with 10.5.1

START REPLICA is an alias for START SLAVE from MariaDB 10.5.1.

See Also

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