COM_BINLOG_DUMP

This command is sent by a replica to the primary server to request the start of the binary log event stream from a specific file and position.

This is a command the replica sends to the master after COM_REGISTER_SLAVE.

The master server sends the binlog events from the requested file and position, or if GTID registration is in use, from the GTID value set in the earlier registration phase.

The payload is:

• uint<1> command (COM_BINLOG_DUMP = 0x12).

• uint<4> The requested binlog position.

• uint<2> Flags.

• uint<4> Slave server_id.

• string The requested binlog file name.

Note

• Flags, usually set to 0. It can be set to BINLOG_SEND_ANNOTATE_ROWS_EVENT (0x02) if the replica server wants to receive the MariaDB 10 ANNOTATE_ROWS events. It can also be set to BINLOG_DUMP_NON_BLOCK (1), in the case the replica is receiving an EOF packet after the last event sent by the master.

• Requested binlog position can be 4 when registering to master server for the very first time or when requesting events from a particular binlog file from the beginning of it.

• The requested binlog file can empty when registering for the very first time if master log file is unknown or with GTID registration (not required).

• After sending events to the replica the server kills the connection.

When replication resumes or it is restarted (STOP REPLICA; START REPLICA), the replica server always sends the latest binlog file name and position, even if GTID registration is in place.

Example of COM_BINLOG_DUMP

1b 00 00 00 12 34 06 00    00 02 00 75 27 00 00 6d    .....4.....u'..m
  79 73 71 6c 2d 62 69 6e    2e 30 30 30 30 33 34       ysql-bin.000034

After 4 bytes network protocol header we can see:

• Command [1] = 12.

• Requested binlog position [4] = 34 06 00 00 => 00 00 06 34 = 1588.

• Flags [2] = 02 00 => 2 = BINLOG_SEND_ANNOTATE_ROWS_EVENT.

• Binlog file[n] = mysql-bin.000034.

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