MySQL 8与复制可观察性
2023-08-26 18:50 abce 阅读(124) 评论(0) 编辑 收藏 举报许多老MySQL DBA都使用show replica status中的seconds_behind_source来了解(异步)复制的状态和正确执行情况。
不过，MySQL复制已经有了很大的发展，复制团队已经努力为MySQL的所有复制方式提供了大量有用的信息。
例如，增加了并行复制、组复制......所有这些信息都是老的show replica status结果中缺少的。
performance_schema为监控和观察复制过程提供了更好的方法。
目前，performance_schema中有15个表与复制相关：
+------------------------------------------------------+ | Tables_in_performance_schema (replication%) | +------------------------------------------------------+ | replication_applier_configuration | | replication_applier_filters | | replication_applier_global_filters | | replication_applier_status | | replication_applier_status_by_coordinator | | replication_applier_status_by_worker | | replication_asynchronous_connection_failover | | replication_asynchronous_connection_failover_managed | | replication_connection_configuration | | replication_connection_status | | replication_group_communication_information | | replication_group_configuration_version | | replication_group_member_actions | | replication_group_member_stats | | replication_group_members | +------------------------------------------------------+
但是，要理解这些指标的含义以及在哪里可以找到对我们这些MySQL DBA很重要的有用信息，确实并非易事：比如复制是否落后于源库？
可以在sys库中创建一些视图，使用这些指标中的大多数指标来获取相关的信息：mysql_8_replication_observability.sql。下载地址：https://gist.github.com/lefred/1bad64403923664a14e0f20f572d7526
下面来看看这写视图。
复制延迟：
select * from sys.replication_lag; +--------------+-----------------------+------------------------+ | channel_name | max_lag_from_original | max_lag_from_immediate | +--------------+-----------------------+------------------------+ | | 0 | 0 | +--------------+-----------------------+------------------------+
复制状态：
>select * from sys.replication_status; +---------+----------+----------+---------+-------------------+--------------------+ | channel | io_state | co_state | w_state | lag_from_original | lag_from_immediate | +---------+----------+----------+---------+-------------------+--------------------+ | (1) | ON | ON | ON | none | none | | (2) | ON | ON | ON | none | none | | (3) | ON | ON | ON | none | none | | (4) | ON | ON | ON | none | none | +---------+----------+----------+---------+-------------------+--------------------+
查看复制更详细的信息：
>select * from sys.replication_status_full; +---------+---------------+------+-----------+--------------------------------------+------------+----------------------------+--------------------+----------+----------------------------------+----------+-----------+----------------------------+----------+----------------------------------------------------------+----------+-----------+----------------------------+---------+---------------------------------------+---------+----------+----------------------------+-------------------------+--------------------+-------------------+--------------------+----------------+-------------------+------------+-----------------------------------------------+-----------------------------------------------+--------------------------+ | channel | host | port | user | source_uuid | group_name | last_heartbeat_timestamp | heartbeat_interval | io_state | io_thread_state | io_errno | io_errmsg | io_errtime | co_state | co_thread_state | co_errno | co_errmsg | co_errtime | w_state | w_thread_state | w_errno | w_errmsg | w_errtime | time_since_last_message | applier_busy_state | lag_from_original | lag_from_immediate | transport_time | time_to_relay_log | apply_time | last_applied_transaction | last_queued_transaction | queued_gtid_set_to_apply | +---------+---------------+------+-----------+--------------------------------------+------------+----------------------------+--------------------+----------+----------------------------------+----------+-----------+----------------------------+----------+----------------------------------------------------------+----------+-----------+----------------------------+---------+---------------------------------------+---------+----------+----------------------------+-------------------------+--------------------+-------------------+--------------------+----------------+-------------------+------------+-----------------------------------------------+-----------------------------------------------+--------------------------+ | (1) | 192.168.137.1 | 3306 | repl_test | 125fcb39-eb11-11ed-9aec-235056b0rhj3 | | 2023-08-18 14:38:20.978058 | 30.000 | ON | Waiting for source to send event | 0 | | 0000-00-00 00:00:00.000000 | ON | Replica has read all relay log; waiting for more updates | 0 | | 0000-00-00 00:00:00.000000 | ON | Waiting for an event from Coordinator | 0 | | 0000-00-00 00:00:00.000000 | 00:00:01.656046 | IDLE | none | none | 79.00 us | 14.00 us | 2.50 ms | 125fcb39-eb11-11ed-9aec-235056b0rhj3:82415939 | 125fcb39-eb11-11ed-9aec-235056b0rhj3:82415939 | | | (2) | 192.168.137.1 | 3306 | repl_test | 125fcb39-eb11-11ed-9aec-235056b0rhj3 | | 2023-08-18 14:38:20.978058 | 30.000 | ON | Waiting for source to send event | 0 | | 0000-00-00 00:00:00.000000 | ON | Replica has read all relay log; waiting for more updates | 0 | | 0000-00-00 00:00:00.000000 | ON | Waiting for an event from Coordinator | 0 | | 0000-00-00 00:00:00.000000 | 00:00:01.656046 | IDLE | none | none | 79.00 us | 14.00 us | 2.63 ms | 125fcb39-eb11-11ed-9aec-235056b0rhj3:82415928 | 125fcb39-eb11-11ed-9aec-235056b0rhj3:82415939 | | | (3) | 192.168.137.1 | 3306 | repl_test | 125fcb39-eb11-11ed-9aec-235056b0rhj3 | | 2023-08-18 14:38:20.978058 | 30.000 | ON | Waiting for source to send event | 0 | | 0000-00-00 00:00:00.000000 | ON | Replica has read all relay log; waiting for more updates | 0 | | 0000-00-00 00:00:00.000000 | ON | Waiting for an event from Coordinator | 0 | | 0000-00-00 00:00:00.000000 | 00:00:01.656046 | IDLE | none | none | 79.00 us | 14.00 us | 2.63 ms | 125fcb39-eb11-11ed-9aec-235056b0rhj3:82415929 | 125fcb39-eb11-11ed-9aec-235056b0rhj3:82415939 | | | (4) | 192.168.137.1 | 3306 | repl_test | 125fcb39-eb11-11ed-9aec-235056b0rhj3 | | 2023-08-18 14:38:20.978058 | 30.000 | ON | Waiting for source to send event | 0 | | 0000-00-00 00:00:00.000000 | ON | Replica has read all relay log; waiting for more updates | 0 | | 0000-00-00 00:00:00.000000 | ON | Waiting for an event from Coordinator | 0 | | 0000-00-00 00:00:00.000000 | 00:00:01.656046 | IDLE | none | none | 79.00 us | 14.00 us | 3.24 ms | 125fcb39-eb11-11ed-9aec-235056b0rhj3:82415879 | 125fcb39-eb11-11ed-9aec-235056b0rhj3:82415939 | | +---------+---------------+------+-----------+--------------------------------------+------------+----------------------------+--------------------+----------+----------------------------------+----------+-----------+----------------------------+----------+----------------------------------------------------------+----------+-----------+----------------------------+---------+---------------------------------------+---------+----------+----------------------------+-------------------------+--------------------+-------------------+--------------------+----------------+-------------------+------------+-----------------------------------------------+-----------------------------------------------+--------------------------+
