The Ultimate Guide to High Availability with MariaDB

GTID_LIST_EVENT

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Logged in every binlog to record the current replication state. Consists of the last GTID seen for each replication domain.

The Global Transaction ID, GTID for short, consists of three components:

  • replication domain ID
  • master server ID
  • sequence ID

It's represented as three numbers separated with dashes '-'
For example: 1-1222-1011

It's usually written after the Format Description Event.

Note: In case of encrypted binlog files (encrypt_binlog is set to ON), this event is written just after the START_ENCRYPTION_EVENT

  • Event type is 163 (0xa3)

Fields

The minimum content size for 1 GTID is: 4 + (4 + 4 + 8) * 1 = 20 bytes

Example With 1 GTID, With CRC32

From the mysqlbinlog utility:

170824 9:52:04 server id 10124 end_log_pos 292 CRC32 0xb6d8f0a8 Gtid list [0-10124-3584]

a4 85 9e 59 a3 8c 27 00  00 2b 00 00 00 24 01 00  ...Y..'..+...$..
00 00 00 01 00 00 00 00  00 00 00 8c 27 00 00 00  ............'...
0e 00 00 00 00 00 00 a8  f0 d8 b6                 ..........

Header, 19 Bytes

  • Event Time = a4 85 9e 59 ===> 2017-08-24 9:52:04
  • Event Type = a3 => 163
  • Server_id = 8c 27 00 00 => 00 00 27 8c => 10124
  • Event Size = 2b => 43 (header[19] + 1 GTID(20 bytes) + CRC32[4]
  • Next Pos = 24 01 00 00 => 00 00 01 24 => 292
  • Flags = 00 => 0

Content, Variable Size, is (4 + (4 + 4 + 8 ) * n_GTIDs) Bytes

The content example with one GTID is 20 bytes + 4 bytes CRC32:

  • Number of GTIDs[4] = 01 00 00 00 => 1
  • GTID[0] replication_domain[4] = 00 00 00 00 => 0
  • GTID[0] Server_id[4] = 8c 27 00 00 => 00 00 27 8c => 10124
  • GTID[0] Sequence[8] = 00 0e 00 00 00 00 00 00 ===> 3584
  • crc32[4] = a8 f0 d8 b6 => b6 d8 f0 a8 => 0xb6d8f0a8

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