MySQL运维与监控之：MySQL的GTID_EXECUTED：其在binlog中的位置信息
大家好，今天我们来深入探讨MySQL的GTID_EXECUTED，以及它在binlog中位置信息的体现。GTID_EXECUTED是MySQL基于GTID复制机制的核心概念之一，理解它对于MySQL运维、故障排查、数据恢复至关重要。
1. GTID（Global Transaction Identifier）简介
在深入GTID_EXECUTED之前，我们先简单回顾一下GTID。GTID是一个全局唯一的事务标识符，由server_uuid和事务序列号组成，格式为server_uuid:transaction_id。例如：3E11FA47-71CA-11E1-9E33-C80AA9429562:1。
GTID解决了传统基于位点（binlog file name和offset）的复制机制的一些问题，例如：
- 唯一性： GTID保证每个事务在整个集群中都有唯一的标识符，避免了位点复制中可能出现的重复执行或遗漏事务。
- 简化复制配置： 基于GTID的复制可以自动处理故障转移和拓扑变化，无需手动调整复制配置。
- 易于监控和管理： GTID使得监控和管理复制拓扑更加简单，可以清晰地了解每个服务器已经执行了哪些事务。
2. GTID_EXECUTED：已执行GTID集合
GTID_EXECUTED是一个服务器级别的变量，它记录了该服务器已经执行过的所有GTID的集合。这个集合存储在数据字典中，重启后依然有效。
可以通过以下SQL语句查看GTID_EXECUTED的值：
SHOW GLOBAL VARIABLES LIKE 'gtid_executed';输出结果类似：
Variable_name | Value
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