MySQL 高级篇 -- 性能分析

文章目录

一、基础知识
- 1.1 数据库服务器的优化步骤
- 1.2 查看系统性能参数
- 1.3 统计 SQL 查询成本
- 1.4 查看 SQL 执行成本
二、mysqldumpslow 慢日志分析
- 2.1 相关变量
- 2.2 案例准备
- 2.3 测试
- 2.4 工具使用
三、trace 分析优化器执行计划
- 3.1 相关参数
- 3.2 使用分析
四、sys.schema 监控分析视图
- 4.1 视图摘要
- 4.2 视图使用场景
- - 4.2.1 索引情况
  - 4.2.2 表相关
  - 4.2.3 语句相关
  - 4.2.4 IO 相关
  - 4.2.5 Innodb 相关

一、基础知识 1.1 数据库服务器的优化步骤

整个流程划分成了观察（Show status）和行动（Action）两个部分。字母 S 的部分代表观察（会使用相应的分析工具），字母 A 代表的部分是行动（对应分析可以采取的行动）。

优化步骤
代价及成效

1.2 查看系统性能参数

在MySQL中，可以使用SHOW STATUS语句查询一些MySQL数据库服务器的性能参数、执行频率 。

mysql> SHOW STATUS LIKE 'Slow_queries';+---------------+-------+| Variable_name | Value |+---------------+-------+| Slow_queries| 0|+---------------+-------+1 row in set (0.00 sec)mysql> SHOW STATUS LIKE 'Innodb_rows_read';+------------------+---------+| Variable_name| Value|+------------------+---------+| Innodb_rows_read | 8792854 |+------------------+---------+1 row in set (0.00 sec)mysql>

常用参数说明Connections连接MySQL服务器的次数UptimeMySQL服务器的上线时间Slow_queries慢查询的次数Innodb_rows_readSelect查询返回的行数Innodb_rows_inserted执行INSERT操作插入的行数Innodb_rows_updated执行UPDATE操作更新的行数Innodb_rows_deleted执行DELETE操作删除的行数Com_select查询操作的次数Com_insert插入操作的次数（对于批量插入的 INSERT 操作，只累加一次）Com_update更新操作的次数Com_delete删除操作的次数1.3 统计 SQL 查询成本

它是作为比较各个查询之间的开销的一个依据 。
它只能检测比较简单的查询开销，对于包含子查询和union的查询是测试不出来的。
当我们执行查询的时候， MySQL会自动生成一个执行计划，也就是query plan ，而且通常有很多种不同的实现方式，它会选择最低的那一个，而这个cost值就是开销最低的那一个。
它对于比较我们的开销是非常有用的， 特别是我们有好几种查询方式可选的时候 。

mysql> SELECT COUNT(DISTINCT(student_id)) FROM `student_info`;+-----------------------------+| COUNT(DISTINCT(student_id)) |+-----------------------------+|198058 |+-----------------------------+1 row in set (0.67 sec)mysql> SHOW STATUS LIKE 'last_query_cost';+-----------------+---------------+| Variable_name| Value|+-----------------+---------------+| Last_query_cost | 100458.549000 |+-----------------+---------------+1 row in set (0.00 sec)mysql>

1.4 查看 SQL 执行成本

开启 profiling

mysql> show variables like 'profiling';+---------------+-------+| Variable_name | Value |+---------------+-------+| profiling| OFF|+---------------+-------+1 row in set (0.05 sec)mysql>set profiling = 'ON';Query OK, 0 rows affected, 1 warning (0.00 sec)mysql> SELECT * FROM student WHERE stuno = 3455655;+---------+---------+--------+------+---------+| id| stuno| name| age| classId |+---------+---------+--------+------+---------+| 3355654 | 3455655 | uWAJVB |89 |777 |+---------+---------+--------+------+---------+1 row in set (1.97 sec)mysql>

使用 profiling

mysql> SELECT * FROM student WHERE stuno = 3455655;...1 row in set (1.97 sec)mysql> SELECT * FROM student WHERE name = 'JsJtPT';...8 rows in set (0.00 sec)mysql> show profiles;+----------+------------+---------------------------------------------+| Query_ID | Duration| Query|+----------+------------+---------------------------------------------+|1 | 1.98446300 | SELECT * FROM student WHERE stuno = 3455655 ||2 | 0.00596225 | SELECT * FROM student WHERE name = 'JsJtPT' |+----------+------------+---------------------------------------------+2 rows in set, 1 warning (0.00 sec)# 默认展示最近的一条记录 ， 即 ‘Query_ID = 2’mysql> show profile;+--------------------------------+----------+| Status| Duration |+--------------------------------+----------+| starting| 0.000091 || Executing hook on transaction| 0.000006 || starting| 0.000009 || checking permissions| 0.000007 || Opening tables| 0.000053 || init| 0.000006 || System lock| 0.000010 || optimizing| 0.000011 || statistics| 0.001088 || preparing| 0.000023 || executing| 0.004580 || end| 0.000015 || query end| 0.000005 || waiting for handler commit| 0.000013 || closing tables| 0.000011 || freeing items| 0.000022 || cleaning up| 0.000015 |+--------------------------------+----------+17 rows in set, 1 warning (0.00 sec)# 定制化查询某条记录的某些指标mysql> show profile cpu,block io for query 1;+--------------------------------+----------+----------+------------+--------------+---------------+| Status| Duration | CPU_user | CPU_system | Block_ops_in | Block_ops_out |+--------------------------------+----------+----------+------------+--------------+---------------+| starting| 0.000096 | 0.000068 |0.000019 |0 |0 || Executing hook on transaction| 0.000016 | 0.000007 |0.000002 |0 |0 || starting| 0.000008 | 0.000006 |0.000002 |0 |0 || checking permissions| 0.000007 | 0.000005 |0.000001 |0 |0 || Opening tables| 0.000040 | 0.000031 |0.000009 |0 |0 || init| 0.000007 | 0.000006 |0.000002 |0 |0 || System lock| 0.000021 | 0.000011 |0.000003 |0 |0 || optimizing| 0.000012 | 0.000010 |0.000002 |0 |0 || statistics| 0.000020 | 0.000015 |0.000005 |0 |0 || preparing| 0.000020 | 0.000016 |0.000004 |0 |0 || executing| 1.963674 | 1.342543 |0.115670 |316896 |0 || end| 0.000023 | 0.000016 |0.000004 |0 |0 || query end| 0.000007 | 0.000005 |0.000002 |0 |0 || waiting for handler commit| 0.000013 | 0.000011 |0.000003 |0 |0 || closing tables| 0.000012 | 0.000009 |0.000002 |0 |0 || freeing items| 0.000132 | 0.000024 |0.000007 |0 |0 || logging slow query| 0.020331 | 0.000175 |0.000049 |416 |8 || cleaning up| 0.000026 | 0.000020 |0.000006 |0 |0 |+--------------------------------+----------+----------+------------+--------------+---------------+18 rows in set, 1 warning (0.00 sec)mysql>

常用查询参数

选项说明ALL显示所有的开销信息BLOCK IO显示块IO开销CONTEXT SWITCHES上下文切换开销CPU显示CPU开销信息IPC显示发送和接收开销信息MEMORY显示内存开销信息PAGE FAULTS显示页面错误开销信息SOURCE显示和 Source_function, Source_file, Source_line 相关的开销信息SWAPS显示交换次数开销信息二、mysqldumpslow 慢日志分析

在生产环境中，如果要手工从慢日志中查找、分析 SQL 显然是个体力活， MySQL 提供了慢查询日志分析工具 mysqldumpslow 。

2.1 相关变量

启开状态

mysql> SHOW VARIABLES LIKE 'slow_query_log%';+---------------------+--------------------------------------+| Variable_name| Value|+---------------------+--------------------------------------+| slow_query_log| OFF|| slow_query_log_file | /var/lib/mysql/5157698acdb3-slow.log |+---------------------+--------------------------------------+2 rows in set (0.00 sec)mysql>

记录阈值

mysql> SHOW VARIABLES LIKE '%long_query_time%';+-----------------+-----------+| Variable_name| Value|+-----------------+-----------+| long_query_time | 10.000000 |+-----------------+-----------+1 row in set (0.00 sec)mysql>

慢查询数目

mysql> SHOW GLOBAL STATUS LIKE '%Slow_queries%';+---------------+-------+| Variable_name | Value |+---------------+-------+| Slow_queries| 0|+---------------+-------+1 row in set (0.01 sec)mysql>

2.2 案例准备

建表

CREATE TABLE `student` (`id` INT(11) NOT NULL AUTO_INCREMENT,`stuno` INT NOT NULL ,`name` VARCHAR(20) DEFAULT NULL,`age` INT(3) DEFAULT NULL,`classId` INT(11) DEFAULT NULL,PRIMARY KEY (`id`)) ENGINE=INNODB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

设置参数 log_bin_trust_function_creators

# 创建函数 ， 假如报错：This function has none of DETERMINISTIC......# 命令开启：允许创建函数设置：set global log_bin_trust_function_creators=1;

创建函数

# 函数1：创建随机产生字符串函数DELIMITER //CREATE FUNCTION rand_string(n INT)RETURNS VARCHAR(255) #该函数会返回一个字符串BEGINDECLARE chars_str VARCHAR(100) DEFAULT 'abcdefghijklmnopqrstuvwxyzABCDEFJHIJKLMNOPQRSTUVWXYZ';DECLARE return_str VARCHAR(255) DEFAULT '';DECLARE i INT DEFAULT 0;WHILE i < n DOSET return_str = CONCAT(return_str, SUBSTRING(chars_str, FLOOR(1 + RAND() * 52), 1));SET i = i + 1;END WHILE;RETURN return_str;END //DELIMITER ;#函数2：创建随机数函数DELIMITER //CREATE FUNCTION rand_num (from_num INT ,to_num INT) RETURNS INT(11)BEGINDECLARE i INT DEFAULT 0;SET i = FLOOR(from_num + RAND() * (to_num - from_num + 1)) ;RETURN i;END //DELIMITER ;

创建存储过程

DELIMITER //CREATE PROCEDURE insert_stu1( START INT , max_num INT )BEGINDECLARE i INT DEFAULT 0;SET autocommit = 0; #设置手动提交事务REPEAT #循环SET i = i + 1; #赋值INSERT INTO student (stuno, NAME ,age ,classId )VALUES ((START+i), rand_string(6), rand_num(10,100), rand_num(10,1000));UNTIL i = max_numEND REPEAT;COMMIT; #提交事务END //DELIMITER ;

调用存储过程

#调用刚刚写好的函数, 4000000条记录,从100001号开始CALL insert_stu1(100001,4000000); 2.3 测试

打开慢日志记录并调低慢查询的记录阈值

【MySQL 高级篇 -- 性能分析】

mysql> SET GLOBAL slow_query_log=on;Query OK, 0 rows affected (0.32 sec)mysql> set global long_query_time = 1;Query OK, 0 rows affected (0.00 sec)mysql>

测试

mysql> SELECT * FROM student WHERE stuno = 3455655;+---------+---------+--------+------+---------+| id| stuno| name| age| classId |+---------+---------+--------+------+---------+| 3355654 | 3455655 | uWAJVB |89 |777 |+---------+---------+--------+------+---------+1 row in set (1.90 sec)mysql> SELECT * FROM student WHERE name = 'JsJtPT';+---------+---------+--------+------+---------+| id| stuno| name| age| classId |+---------+---------+--------+------+---------+|242278 |342279 | JsJtPT |100 |352 ||611433 |711434 | jSJTpT |51 |683 || 1000005 | 1100006 | JsJtPT |99 |279 || 1612477 | 1712478 | jsjTPt |57 |474 || 2240808 | 2340809 | JSjtpt |98 |729 || 2970233 | 3070234 | JSjtpt |97 |709 || 2992184 | 3092185 | JSjtpt |98 |747 || 3679784 | 3779785 | jSJTpT |52 |707 |+---------+---------+--------+------+---------+8 rows in set (1.68 sec)mysql>

记录

mysql> show status like 'slow_queries';+---------------+-------+| Variable_name | Value |+---------------+-------+| Slow_queries| 2|+---------------+-------+1 row in set (0.12 sec)mysql>

2.4 工具使用

工具简介

root@5157698acdb3:/# mysqldumpslow --helpUsage: mysqldumpslow [ OPTS... ] [ LOGS... ]Parse and summarize the MySQL slow query log. Options are--verboseverbose--debugdebug--helpwrite this text to standard output-vverbose-ddebug-s ORDERwhat to sort by (al, at, ar, c, l, r, t), 'at' is default # 表示按照何种方式排序al: average lock time # 平均锁定时间ar: average rows sent # 平均返回记录at: average query time # 平均查询时间 （默认方式）c: count # 访问次数l: lock time # 锁定时间r: rows sent # 返回记录t: query time# 查询时间-rreverse the sort order (largest last instead of first)-t NUMjust show the top n queries # 即为返回前面多少条的数据-adon't abstract all numbers to N and strings to 'S' # 不将数字抽象成N ， 字符串抽象成S-n NUMabstract numbers with at least n digits within names-g PATTERNgrep: only consider stmts that include this string # 后边搭配一个正则匹配模式 ， 大小写不敏感的-h HOSTNAMEhostname of db server for *-slow.log filename (can be wildcard),default is '*', i.e. match all-i NAMEname of server instance (if using mysql.server startup script)-ldon't subtract lock time from total timeroot@5157698acdb3:/#

按照查询时间排序，查看前五条 SQL 语句

root@5157698acdb3:/# mysqldumpslow -s t -t 5 -a /var/lib/mysql/5157698acdb3-slow.logReading mysql slow query log from /var/lib/mysql/5157698acdb3-slow.logCount: 1Time=1.67s (1s)Lock=0.00s (0s)Rows=8.0 (8), root[root]@localhostSELECT * FROM student WHERE name = 'JsJtPT'Count: 1Time=1.53s (1s)Lock=0.00s (0s)Rows=1.0 (1), root[root]@localhostSELECT * FROM student WHERE stuno = 3455655Died at /usr/bin/mysqldumpslow line 162, <> chunk 2.root@5157698acdb3:/#

mysql> ALTER TABLE student ADD INDEX(name);Query OK, 0 rows affected (21.23 sec)Records: 0Duplicates: 0Warnings: 0mysql> SELECT * FROM student WHERE name = 'JsJtPT';+---------+---------+--------+------+---------+| id| stuno| name| age| classId |+---------+---------+--------+------+---------+|242278 |342279 | JsJtPT |100 |352 ||611433 |711434 | jSJTpT |51 |683 || 1000005 | 1100006 | JsJtPT |99 |279 || 1612477 | 1712478 | jsjTPt |57 |474 || 2240808 | 2340809 | JSjtpt |98 |729 || 2970233 | 3070234 | JSjtpt |97 |709 || 2992184 | 3092185 | JSjtpt |98 |747 || 3679784 | 3779785 | jSJTpT |52 |707 |+---------+---------+--------+------+---------+8 rows in set (0.02 sec)mysql>

其它常用分析语句

# 得到返回记录集最多的10个SQLmysqldumpslow -s r -t 10 /var/lib/mysql/atguigu-slow.log# 得到访问次数最多的10个SQLmysqldumpslow -s c -t 10 /var/lib/mysql/atguigu-slow.log# 得到按照时间排序的前10条里面含有左连接的查询语句mysqldumpslow -s t -t 10 -g "left join" /var/lib/mysql/atguigu-slow.log# 另外建议在使用这些命令时结合 | 和 less 使用  ， 否则有可能出现爆屏情况mysqldumpslow -s r -t 10 /var/lib/mysql/atguigu-slow.log | less

三、trace 分析优化器执行计划 3.1 相关参数

查询

mysql> select @@optimizer_trace;+--------------------------+| @@optimizer_trace|+--------------------------+| enabled=off,one_line=off |+--------------------------+1 row in set (0.00 sec)mysql> select @@end_markers_in_json;+-----------------------+| @@end_markers_in_json |+-----------------------+|0 |+-----------------------+1 row in set (0.00 sec)# 最大能够使用的内存大小mysql> select @@optimizer_trace_max_mem_size;+--------------------------------+| @@optimizer_trace_max_mem_size |+--------------------------------+|1048576 |+--------------------------------+1 row in set (0.00 sec)mysql>

开启

mysql> SET optimizer_trace="enabled=on",end_markers_in_json=on;Query OK, 0 rows affected (0.00 sec)mysql> set optimizer_trace_max_mem_size=1000000;Query OK, 0 rows affected (0.00 sec)mysql>

3.2 使用分析

mysql> select * from student where id < 10;+----+--------+--------+------+---------+| id | stuno| name| age| classId |+----+--------+--------+------+---------+|1 | 100002 | ACnHyt |51 |170 ||2 | 100003 | xNvPNu |70 |166 ||3 | 100004 | PBlBXi |10 |547 ||4 | 100005 | JOSWhT |94 |45 ||5 | 100006 | uSfZFc |47 |915 ||6 | 100007 | rYRpXS |48 |551 ||7 | 100008 | yKesCJ |52 |466 ||8 | 100009 | Vjkvxc |91 |332 ||9 | 100010 | WLPOBp |94 |726 |+----+--------+--------+------+---------+9 rows in set (0.00 sec)mysql> select * from information_schema.optimizer_trace\G*************************** 1. row ***************************// 第1部分：查询语句QUERY: select * from student where id < 10// 第2部分：QUERY字段对应语句的跟踪信息TRACE: {"steps": [{"join_preparation": { // 预备工作"select#": 1,"steps": [{"expanded_query": "/* select#1 */ select `student`.`id` AS `id`,`student`.`stuno` AS `stuno`,`student`.`name` AS `name`,`student`.`age` AS `age`,`student`.`classId` AS `classId` from `student` where (`student`.`id` < 10)"}] /* steps */} /* join_preparation */},{"join_optimization": { // 进行优化"select#": 1,"steps": [{"condition_processing": { // 条件处理"condition": "WHERE","original_condition": "(`student`.`id` < 10)","steps": [{"transformation": "equality_propagation","resulting_condition": "(`student`.`id` < 10)"},{"transformation": "constant_propagation","resulting_condition": "(`student`.`id` < 10)"},{"transformation": "trivial_condition_removal","resulting_condition": "(`student`.`id` < 10)"}] /* steps */} /* condition_processing */},{"substitute_generated_columns": { // 替换生成的列} /* substitute_generated_columns */},{"table_dependencies": [ // 表的依赖关系{"table": "`student`","row_may_be_null": false,"map_bit": 0,"depends_on_map_bits": [] /* depends_on_map_bits */}] /* table_dependencies */},{"ref_optimizer_key_uses": [ // 使用键] /* ref_optimizer_key_uses */},{"rows_estimation": [ // 行判断{"table": "`student`","range_analysis": {"table_scan": {"rows": 3990175,"cost": 406233} /* table_scan */, // 扫描表"potential_range_indexes": [ // 潜在的范围索引{"index": "PRIMARY","usable": true,"key_parts": ["id"] /* key_parts */},{"index": "name","usable": true,"key_parts": ["name","id"] /* key_parts */}] /* potential_range_indexes */,"setup_range_conditions": [] /* setup_range_conditions */, // 设置范围条件"group_index_range": {"chosen": false,"cause": "not_group_by_or_distinct"} /* group_index_range */,"skip_scan_range": {"potential_skip_scan_indexes": [{"index": "PRIMARY","usable": false,"cause": "query_references_nonkey_column"},{"index": "name","usable": false,"cause": "query_references_nonkey_column"}] /* potential_skip_scan_indexes */} /* skip_scan_range */,"analyzing_range_alternatives": { // 分析范围选项"range_scan_alternatives": [{"index": "PRIMARY","ranges": ["id < 10"] /* ranges */,"index_dives_for_eq_ranges": true,"rowid_ordered": true,"using_mrr": false,"index_only": false,"in_memory": 0.386281,"rows": 9,"cost": 1.62734,"chosen": true},{"index": "name","chosen": false,"cause": "no_valid_range_for_this_index"}] /* range_scan_alternatives */,"analyzing_roworder_intersect": {"usable": false,"cause": "too_few_roworder_scans"} /* analyzing_roworder_intersect */} /* analyzing_range_alternatives */,"chosen_range_access_summary": { // 选择范围访问摘要"range_access_plan": {"type": "range_scan","index": "PRIMARY","rows": 9,"ranges": ["id < 10"] /* ranges */} /* range_access_plan */,"rows_for_plan": 9,"cost_for_plan": 1.62734,"chosen": true} /* chosen_range_access_summary */} /* range_analysis */}] /* rows_estimation */},{"considered_execution_plans": [ // 考虑执行计划{"plan_prefix": [] /* plan_prefix */,"table": "`student`","best_access_path": { // 最佳访问路径"considered_access_paths": [{"rows_to_scan": 9,"access_type": "range","range_details": {"used_index": "PRIMARY"} /* range_details */,"resulting_rows": 9,"cost": 2.52734,"chosen": true}] /* considered_access_paths */} /* best_access_path */,"condition_filtering_pct": 100, // 行过滤百分比"rows_for_plan": 9,"cost_for_plan": 2.52734,"chosen": true}] /* considered_execution_plans */},{"attaching_conditions_to_tables": { // 将条件附加到表上"original_condition": "(`student`.`id` < 10)","attached_conditions_computation": [] /* attached_conditions_computation */,"attached_conditions_summary": [ // 附加条件概要{"table": "`student`","attached": "(`student`.`id` < 10)"}] /* attached_conditions_summary */} /* attaching_conditions_to_tables */},{"finalizing_table_conditions": [{"table": "`student`","original_table_condition": "(`student`.`id` < 10)","final_table_condition": "(`student`.`id` < 10)"}] /* finalizing_table_conditions */},{"refine_plan": [ // 精简计划{"table": "`student`"}] /* refine_plan */}] /* steps */} /* join_optimization */},{"join_execution": { // 执行"select#": 1,"steps": [] /* steps */} /* join_execution */}] /* steps */}// 第3部分：跟踪信息过长时 ， 被截断的跟踪信息的字节数 。MISSING_BYTES_BEYOND_MAX_MEM_SIZE: 0 // 丢失的超出最大容量的字节// 第4部分：执行跟踪语句的用户是否有查看对象的权限 。当不具有权限时 ， 该列信息为1且TRACE字段为空 ， 一般在// 调用带有SQL SECURITY DEFINER的视图或者是存储过程的情况下 ， 会出现此问题 。INSUFFICIENT_PRIVILEGES: 0 //缺失权限1 row in set (0.03 sec)mysql>

四、sys.schema 监控分析视图 4.1 视图摘要视图说明主机相关以host_summary开头，主要汇总了IO延迟的信息。Innodb相关以innodb开头，汇总了innodb buffer信息和事务等待innodb锁的信息。I/o相关以io开头，汇总了等待I/O、I/O使用量情况。内存使用情况以memory开头，从主机、线程、事件等角度展示内存的使用情况连接与会话信息processlist和session相关视图，总结了会话相关信息。表相关以schema_table开头的视图，展示了表的统计信息。索引信息统计了索引的使用情况，包含冗余索引和未使用的索引情况。语句相关以statement开头，包含执行全表扫描、使用临时表、排序等的语句信息。用户相关以user开头的视图，统计了用户使用的文件I/O、执行语句统计信息。等待事件相关信息以wait开头，展示等待事件的延迟情况。4.2 视图使用场景 4.2.1 索引情况

#1. 查询冗余索引select * from sys.schema_redundant_indexes;#2. 查询未使用过的索引select * from sys.schema_unused_indexes;#3. 查询索引的使用情况select index_name,rows_selected,rows_inserted,rows_updated,rows_deletedfrom sys.schema_index_statistics where table_schema='dbname' ;

4.2.2 表相关

# 1. 查询表的访问量select table_schema,table_name,sum(io_read_requests+io_write_requests) as io fromsys.schema_table_statistics group by table_schema,table_name order by io desc;# 2. 查询占用bufferpool较多的表select object_schema,object_name,allocated,datafrom sys.innodb_buffer_stats_by_table order by allocated limit 10;# 3. 查看表的全表扫描情况select * from sys.statements_with_full_table_scans where db='dbname';

4.2.3 语句相关

#1. 监控SQL执行的频率select db,exec_count,query from sys.statement_analysisorder by exec_count desc;#2. 监控使用了排序的SQLselect db,exec_count,first_seen,last_seen,queryfrom sys.statements_with_sorting limit 1;#3. 监控使用了临时表或者磁盘临时表的SQLselect db,exec_count,tmp_tables,tmp_disk_tables,queryfrom sys.statement_analysis where tmp_tables>0 or tmp_disk_tables >0order by (tmp_tables+tmp_disk_tables) desc;

4.2.4 IO 相关

#1. 查看消耗磁盘IO的文件select file,avg_read,avg_write,avg_read+avg_write as avg_iofrom sys.io_global_by_file_by_bytes order by avg_read limit 10;

4.2.5 Innodb 相关 # 1. 行锁阻塞情况select * from sys.innodb_lock_waits;