作者：杨涛涛
资深数据库专家，专研 MySQL 十余年。擅长 MySQL、PostgreSQL、MongoDB 等开源数据库相关的备份恢复、SQL 调优、监控运维、高可用架构设计等。目前任职于爱可生，为各大运营商及银行金融企业提供 MySQL 相关技术支持、MySQL 相关课程培训等工作。
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在 GITHUB 上闲逛，发现一款开源的 MySQL Shell 插件，安装配置好后，可以额外增加 MySQL Shell 的组件多样性以及类似早期 MySQL Utilities 工具集的各种功能（MySQL Utilities 已经不再开发了！ ）。
插件地址：https://github.com/lefred/mysqlshell-plugins
安装非常简单，创建对应的 MySQL Shell Plugins 目录，完了把插件整个拷贝到此即可。
mkdir -p ~/.mysqlsh/pluginsgit clone https://kgithub.com/lefred/mysqlshell-plugins.git ~/.mysqlsh/plugins
我的OS环境是 Fedora Server 37 ，拷贝完对应目录后，提示各种 Python 包依赖错误，可以根据日志~/.mysqlsh/mysqlsh.log 内容提示依次解决，此处省略步骤。
解决好各种依赖包后，进入 MySQL Shell 命令行，可以看到出现很多新的组件：audit、check、config 等等。这里就不贴这些内容了。
我来简单演示其中几个组件：
第一，复制组件：replication。
目前的拓扑是这样的：我本地搭了三个实例 127.0.0.1:3310 、127.0.0.1:3311 、127.0.0.1:3312 。这三个实例组建了一个副本集，3310是主，3311和3312是从。
MySQL localhost:3311 ssl Py > rs.status()
{
"replicaSet": {
"name": "rs1",
"primary": "127.0.0.1:3310",
...
"topology": {
"127.0.0.1:3310": {
"address": "127.0.0.1:3310",
"instanceRole": "PRIMARY",
"mode": "R/W",
"status": "ONLINE"
},
"127.0.0.1:3311": {
"address": "127.0.0.1:3311",
"instanceRole": "SECONDARY",
"mode": "R/O",
...
"status": "ONLINE"
},
"127.0.0.1:3312": {
"address": "127.0.0.1:3312",
"instanceRole": "SECONDARY",
"mode": "R/O",
...
"status": "ONLINE"
}
},
"type": "ASYNC"
}
}
这里我主动制造了一个错误，完后连接到其中一台从库上使用 replication.status() 获取本机复制状态：此时 SQL 线程停止，并且显示延迟20秒。
MySQL localhost:3312 ssl Py > replication.status(); +--------------+-----------+------------+------------+ | channel_name | IO_thread | SQL_thread | lag_in_sec | +--------------+-----------+------------+------------+ | | ON | OFF | 20 | +--------------+-----------+------------+------------+
使用 replication.error() 来获取详细错误：发现GTID 923dad27-8528-11ed-8796-080027382b72:78 执行失败，失败原因是主键重复。
MySQL localhost:3312 ssl Py > replication.error() Applier error: 2022-12-26 22:37:35.146527 : Coordinator stopped because there were error(s) in the worker(s). The most recent failure being: Worker 1 failed executing transaction '923dad27-8528-11ed-8796-080027382b72:78' at master log ytt-pc-bin.000003, end_log_pos 1105. See error log and/or performance_schema.replication_applier_status_by_worker table for more details about this failure or others, if any. 2022-12-26 22:37:35.146532 : Worker 1 failed executing transaction '923dad27-8528-11ed-8796-080027382b72:78' at master log ytt-pc-bin.000003, end_log_pos 1105; Could not execute Write_rows event on table ytt.t1; Duplicate entry '10' for key 't1.PRIMARY', Error_code: 1062; handler error HA_ERR_FOUND_DUPP_KEY; the event's master log ytt-pc-bin.000003, end_log_pos 1105
再使用 replication.get_gtid_to_skip() 来确认具体的 GTID ：确认无疑是923dad27-8528-11ed-8796-080027382b72:78。
MySQL localhost:3312 ssl Py > replication.get_gtid_to_skip() +--------------+-----------------------------------------+ | channel_name | gtid_to_skip | +--------------+-----------------------------------------+ | | 923dad27-8528-11ed-8796-080027382b72:78 | +--------------+-----------------------------------------+
使用 replication.skip_error() 来跳过这个 GTID ：
MySQL localhost:3312 ssl Py > replication.skip_error(); skiping 923dad27-8528-11ed-8796-080027382b72:78 for replication channel ''...
完后在从库重启复制线程：stop replica;start replica;
MySQL localhost:3312 ssl SQL > stop replica;start replica; Query OK, 0 rows affected (0.0194 sec) Query OK, 0 rows affected (0.0347 sec)
再次查看复制是否有错误以及当前复制状态：没有错误，一切恢复正常。
MySQL localhost:3312 ssl Py > replication.error(); no error MySQL localhost:3312 ssl Py > replication.status(); +--------------+-----------+------------+------------+ | channel_name | IO_thread | SQL_thread | lag_in_sec | +--------------+-----------+------------+------------+ | | ON | ON | 0 | +--------------+-----------+------------+------------+
第二、获取锁相关数据的组件：locks 。
locks 组件可以获取当前事务的锁数据，包括当前锁持有以及锁等待相关线程 ID 、锁持有时间、内存占用、锁的具体行数等。下面使用 locks.get_locks() 来获取当前锁相关数据：
MySQL localhost:3310 ssl Py > locks.get_locks() +-----------------+--------------+-------------+-----------+----------------+-------------------+-------------------+-------------------------------------------------------------------+ | mysql_thread_id | trx_duration | cpu_latency | memory | row_locks_held | row_locks_pending | tables_with_locks | current_statement | +-----------------+--------------+-------------+-----------+----------------+-------------------+-------------------+-------------------------------------------------------------------+ | 25 | 4.43 min | 0 ps | 2.07 MiB | 3 | 0 | ytt.t1 | NULL | | 29 | 17.51 s | 0 ps | 2.49 MiB | 1 | 0 | ytt.t1 | update t1 set r1 = 100 where id =10 | | 7 | 10.69 ms | | 15.66 KiB | 0 | 0 | NULL | NULL | | 27 | 269.67 us | 0 ps | 10.31 MiB | 0 | 0 | NULL | SELECT thr.processlist_id AS m ... IT DESC LIMIT 10 | | 13 | 136.45 us | 0 ps | 1.19 MiB | 0 | 0 | NULL | NULL | +-----------------+--------------+-------------+-----------+----------------+-------------------+-------------------+-------------------------------------------------------------------+
根据后续提示，还可以获取更多的数据：比如线程25，持有 IX 意向锁以及 X 记录锁，以及当前等待此锁的 SQL 语句；线程29申请X记录锁却被线程25阻塞。
For which thread_id do you want to see locks ? (25) : 25
Metadata Locks:
---------------
GRANTED SHARED_WRITE on ytt.t1
Data Locks:
-----------
GRANTED TABLE (IX) LOCK ON ytt.t1
GRANTED RECORD (X) LOCK ON ytt.t1 (PRIMARY) (id=supremum pseudo-record)
(id=10)
BLOCKING RECORD (X,REC_NOT_GAP) LOCK ON ytt.t1 FOR 12 SECONDS (mysql_thread_id: 29)
Statement we are blocking:
--------------------------
update t1 set r1 = 100 where id =10
For which thread_id do you want to see locks ? (25) : 29
Metadata Locks:
---------------
GRANTED SHARED_WRITE on ytt.t1
Data Locks:
-----------
GRANTED TABLE (IX) LOCK ON ytt.t1
WAITING RECORD (X,REC_NOT_GAP) LOCK ON ytt.t1 (PRIMARY) (id=10)
BLOCKED FOR 8 SECONDS BY (mysql_thread_id: 25)
第三、获取语句执行的 profiles 数据：profiling 组件。
先执行 profiling.start() ，完后执行些语句，再用 profiling.get() 来获取具体的 profiles 数据，最后再关闭 profiling 收集。
MySQL localhost:3310 ssl ytt Py > profiling.get() Last 5 events from the proccess list id: @@pseudo_thread_id ----------------------------------------------------------- ---Events before profiling was started are in orange--- 1563 : select schema() 1555 : help 'profiling' 1551 : profiling.get() 1531 : select * from t1 order by rand() limit 10 1512 : select count(*) from t1 Which event do you want to profile ? : 1531 Profiling of: ------------- select * from t1 order by rand() limit 10 duration: 0.0162 +------------------------------------------------+----------+ | Stage | Duration | +------------------------------------------------+----------+ | stage/sql/starting | 0.0000 | | stage/sql/Executing hook on transaction begin. | 0.0000 | | stage/sql/starting | 0.0000 | | stage/sql/checking permissions | 0.0000 | | stage/sql/Opening tables | 0.0000 | | stage/sql/init | 0.0000 | | stage/sql/System lock | 0.0000 | | stage/sql/optimizing | 0.0000 | | stage/sql/statistics | 0.0000 | | stage/sql/preparing | 0.0000 | | stage/sql/Creating tmp table | 0.0000 | | stage/sql/executing | 0.0160 | | stage/sql/end | 0.0000 | | stage/sql/query end | 0.0000 | | stage/sql/waiting for handler commit | 0.0000 | | stage/sql/closing tables | 0.0000 | | stage/sql/freeing items | 0.0000 | | stage/sql/cleaning up | 0.0000 | +------------------------------------------------+----------+ Don't forget to stop the profiling when done.
第四、连接主库使用 innodb 组件查看有碎片的表，并且获取表大小、索引大小、碎片率等数据。
MySQL localhost:3310 ssl ytt Py > innodb.get_fragmented_tables_disk() Warning: information_schema_stats_expiry is set to 86400. Do you want to change it ? (y/N) : n +--------+-------+-----------+------------+------------+-----------+-----------+-------------+--------+ | NAME | ROWS | DATA_SIZE | INDEX_SIZE | TOTAL_SIZE | DATA_FREE | FILE_SIZE | WASTED_SIZE | FREE | +--------+-------+-----------+------------+------------+-----------+-----------+-------------+--------+ | ytt/t1 | 28861 | 4.52 MiB | 0 bytes | 4.52 MiB | 4.00 MiB | 12.00 MiB | 7.48 MiB | 62.37% | +--------+-------+-----------+------------+------------+-----------+-----------+-------------+--------+ Don't forget to run 'ANALYZE TABLE ...' for a more accurate result.
第五、使用 check 组件来获取 binlog 的 IO 数据：由于格式不好看，我截了张图。可以展示现存所有 binlog 文件的读写频率、读写数据等信息。
