mysql8.0使用ps_trace_statement_digest()追踪语句执行流程

mysql8.0使用ps_trace_statement_digest()追踪语句执行流程

简介

根据指定的digest监控events_statements_history_long和events_stages_ history_long表，以获取指定digest相关的事件,分析的结果包括摘要数据以及详细信息。

参数

• Digest: 语句的标识， 可以查看events_statements_summary_by_digest获取追踪语句对应得digest值
• Runtime: 监控时长
• Poll Interval: 采集间隔时间
• Refresh: 是否在启动前先truncate表events_statements_history_long)， events_stages_history_long
• Auto Setup: 是否自动启用所需要的consumers

常见用法

1. 查看events_statements_summary_by_digest表获取语句对应的digest，也可以直接SET @digest = STATEMENT_DIGEST('BEGIN');，然后digest参数直接写@digest

   SELECT 
       DIGEST, DIGEST_TEXT
   FROM
       performance_schema.events_statements_summary_by_digest
   WHERE
       DIGEST_TEXT LIKE '%INSERT%'
   LIMIT 1;
   

2. 开始追踪

   CALL sys.ps_trace_statement_digest('0c16682717552abfe94da3598604c606be3dea8fe964e735b267eda666840df8', 60, 0.5, TRUE, TRUE);
   

3. 查看生成结果

   +-------------------+
   | summary           |
   +-------------------+
   | Disabled 1 thread |
   +-------------------+
   1 row in set (0.01 sec)
   
   +--------------------+
   | SUMMARY STATISTICS |
   +--------------------+
   | SUMMARY STATISTICS |
   +--------------------+
   1 row in set (1 min 0.46 sec)
   -- executions 执行次数
   -- exec_time 执行总时长
   -- lock_time 锁等待总时长
   -- rows_sent 发送的总行数
   -- rows_affected 生效的行数
   -- rows_examined 检查的行数
   -- tmp_tables 使用的临时表个数
   -- full_scans 全表扫描次数
   +------------+-----------+-----------+-----------+---------------+---------------+------------+------------+
   | executions | exec_time | lock_time | rows_sent | rows_affected | rows_examined | tmp_tables | full_scans |
   +------------+-----------+-----------+-----------+---------------+---------------+------------+------------+
   |       8898 | 53.57 s   | 953.60 ms |         0 |          8898 |             0 |          0 |          0 |
   +------------+-----------+-----------+-----------+---------------+---------------+------------+------------+
   1 row in set (1 min 0.49 sec)
   -- 这个语句执行过程中产生的event以及对应的延迟
   +------------------------------------------------+-------+-----------+
   | event_name                                     | count | latency   |
   +------------------------------------------------+-------+-----------+
   | stage/sql/waiting for handler commit           |  4204 | 23.21 s   |
   | stage/sql/update                               |  4147 | 565.60 ms |
   | stage/sql/starting                             |  8233 | 284.96 ms |
   | stage/sql/freeing items                        |  4321 | 179.22 ms |
   | stage/sql/Opening tables                       |  4121 | 128.72 ms |
   | stage/sql/closing tables                       |  4190 | 53.89 ms  |
   | stage/sql/System lock                          |  4086 | 26.82 ms  |
   | stage/sql/checking permissions                 |  4111 | 15.21 ms  |
   | stage/sql/init                                 |  4247 | 14.45 ms  |
   | stage/sql/end                                  |  4154 | 10.32 ms  |
   | stage/sql/query end                            |  4177 | 4.73 ms   |
   | stage/sql/cleaning up                          |  4155 | 4.30 ms   |
   | stage/sql/Executing hook on transaction begin. |  4110 | 2.97 ms   |
   +------------------------------------------------+-------+-----------+
   13 rows in set (1 min 0.69 sec)
   
   +---------------------------+
   | LONGEST RUNNING STATEMENT |
   +---------------------------+
   | LONGEST RUNNING STATEMENT |
   +---------------------------+
   1 row in set (1 min 0.70 sec)
   -- 这个语句运行时间最长的一次具体信息
   +-----------+-----------+-----------+-----------+---------------+---------------+------------+-----------+
   | thread_id | exec_time | lock_time | rows_sent | rows_affected | rows_examined | tmp_tables | full_scan |
   +-----------+-----------+-----------+-----------+---------------+---------------+------------+-----------+
   |       108 | 201.09 ms | 120.00 us |         0 |             1 |             0 |          0 |         0 |
   +-----------+-----------+-----------+-----------+---------------+---------------+------------+-----------+
   1 row in set (1 min 0.71 sec)
   
   +-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | sql_text                                                                                                                                                                                                                                        |
   +-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | INSERT INTO sbtest5 (id, k, c, pad) VALUES (0, 50316, '86539702156-26530319622-32826744596-31791260593-20574370067-09507408637-55919947787-63819846779-86443542983-67978229383', '43591303543-94583187223-19570388062-12361278127-68855452960') |
   +-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   1 row in set (1 min 0.72 sec)
   
   Empty set (1 min 0.78 sec)
   
   +------------------+
   | summary          |
   +------------------+
   | Enabled 1 thread |
   +------------------+
   1 row in set (1 min 0.85 sec)
   
   Query OK, 0 rows affected (1 min 0.85 sec)
   
   

   参考

   • https://dev.mysql.com/doc/refman/8.0/en/sys-ps-trace-thread.html