Mysql之日常运维命令总结
1、连接MySQL数据库
mysql -uroot -p'password'
mysql -uroot -p'password' -h 127.0.0.1 -P 3306
mysql -uroot -p'password' -S /path/to/mysql.sock
2、查看当前数据库中的会话状态
show processlist;
3、查看当前数据库中的活动会话（排除掉空闲Sleep状态的会话）
select * from information_schema.processlist where command <> 'Sleep';
--8.0以后版本建议使用performance_schema:
select * from performance_schema.processlist where command <> 'Sleep';
--排除掉自己的会话连接
select * from information_schema.processlist where command <> 'Sleep' and id <> connection_id();
select * from performance_schema.processlist where command <> 'Sleep' and id <> connection_id();
--也可以通过其他条件来排查掉自己不想要的会话信息：如user in 或者 db in ,host等查询条件来过滤。
4、查看数据库的总大小
--数据库总大小
select round(sum(data_length+index_length)/1024/1024/1024,2) as 'DBSIZE_GB' from information_schema.tables;
5、查看数据库中各个库的大小合计
--数据库大小信息：
select table_schema,round(sum(data_length+index_length)/1024/1024/1024,3) as 'SIZE_GB' from information_schema.tables where table_schema not in ('sys','mysql','information_schema','performance_schema') group by table_schema ;
6、查看数据库中的TOP 30大表信息
--Top 30大表信息：
select table_schema,table_name,round((data_length+index_length)/1024/1024,2) as 'SIZE_MB',table_rows,engine from information_schema.tables where table_schema not in ('sys','mysql','information_schema','performance_schema') order by 3 desc limit 30 ;
7、查看表和索引的统计信息：
--表统计信息：
select * from mysql.innodb_table_stats where database_name='db_name' and table_name='table_name';
--索引统计信息：
select * from mysql.innodb_index_stats where database_name='' and table_name='' and index_name='idx_name';
8、查询锁等待时持续间大于20秒的SQL信息
SELECT trx_mysql_thread_id AS PROCESSLIST_ID,
NOW(),
TRX_STARTED,
TO_SECONDS(now())-TO_SECONDS(trx_started) AS TRX_LAST_TIME ,
USER,
HOST,
DB,
TRX_QUERY
FROM INFORMATION_SCHEMA.INNODB_TRX trx
JOIN sys.innodb_lock_waits lw ON trx.trx_mysql_thread_id=lw.waiting_pid
JOIN INFORMATION_SCHEMA.processlist pcl ON trx.trx_mysql_thread_id=pcl.id
WHERE trx_mysql_thread_id != connection_id()
AND TO_SECONDS(now())-TO_SECONDS(trx_started) >= 20 ;
9、 查询MySQL锁等待表的详细信息
-- sys库锁等待表：
select * from sys.innodb_lock_waits\G
10、 查询长事务SQL
--长事务（包含未关闭的事务）
SELECT thr.processlist_id AS mysql_thread_id,
concat(PROCESSLIST_USER,'@',PROCESSLIST_HOST) User,
Command,
FORMAT_PICO_TIME(trx.timer_wait) AS trx_duration,
current_statement as `latest_statement`
FROM performance_schema.events_transactions_current trx
INNER JOIN performance_schema.threads thr USING (thread_id)
LEFT JOIN sys.processlist p ON p.thd_id=thread_id
WHERE thr.processlist_id IS NOT NULL
AND PROCESSLIST_USER IS NOT NULL
AND trx.state = 'ACTIVE'
GROUP BY thread_id, timer_wait
ORDER BY TIMER_WAIT DESC LIMIT 10;
11、 查看当前DDL执行的进度
use performance_schema;
select * from setup_instruments where name like 'stage/innodb/alter%';
select * from setup_consumers where name like '%stages%';
--如果上面查询结果为NO，则需要做如下配置：
update set_instrucments set enabled = 'YES' where name like 'stage/innodb/alter%';
update set_consumers set enabled = 'YES' where name like '%stages%';
-- 查询DDL执行的进度：
select stmt.sql_text,
stage.event_name,
concat(work_completed, '/', work_estimated) as progress,
concat(round(100 * work_completed / work_estimated, 2), ' %') as processing_pct,
sys.format_time(stage.timer_wait) as time_costs,
concat(round((stage.timer_end - stmt.timer_start) / 1e12 *
(work_estimated - work_completed) / work_completed,
2),
' s') as remaining_seconds
from performance_schema.events_stages_current stage,
performance_schema.events_statements_current stmt
where stage.thread_id = stmt.thread_id
and stage.nesting_event_id = stmt.event_id\G
12、 执行次数最多的TOP 10 SQL
--执行次数前10 SQL
SELECT QUERY_SAMPLE_TEXT,COUNT_STAR,FIRST_SEEN,LAST_SEEN FROM events_statements_summary_by_digest ORDER BY COUNT_STAR DESC LIMIT 10;
13、平均响应时间最长的TOP 10 SQL
--平均响应时间TOP 10 SQL
SELECT QUERY_SAMPLE_TEXT,AVG_TIMER_WAIT FROM events_statements_summary_by_digest ORDER BY AVG_TIMER_WAIT DESC limit 10;
14、 排序次数最多的TOP 10 SQL
--排序此时最多TOP 10 SQL
SELECT QUERY_SAMPLE_TEXT,SUM_SORT_ROWS FROM events_statements_summary_by_digest ORDER BY SUM_SORT_ROWS DESC LIMIT 10;
15、 扫描记录数最多的 TOP 10 SQL
--扫描行最多的 TOP 10 SQL
SELECT QUERY_SAMPLE_TEXT,SUM_ROWS_EXAMINED FROM events_statements_summary_by_digest ORDER BY SUM_ROWS_EXAMINED DESC LIMIT 10;
16、使用临时表最多的TOP 10 SQL
--使用临时表最多的TOP 10 SQL
SELECT QUERY_SAMPLE_TEXT,SUM_CREATED_TMP_TABLES,SUM_CREATED_TMP_DISK_TABLES FROM events_statements_summary_by_digest ORDER BY SUM_CREATED_TMP_TABLES DESC LIMIT 10;
17、 查询从未使用过的索引
--从未使用过的索引：未使用索引建议直接删除，多余索引如不使用会影响增删改性能，且索引占用磁盘空间。
select * from schema_unused_indexes where object_schema not in ('performance_schema');
18、 查询冗余索引
--冗余索引建议删除
select * from schema_redundant_indexes;
19、 查询数据库中没有主键的表
--查询所有无主键表：
SELECT A.table_schema, A.table_name
FROM information_schema.tables AS A
LEFT JOIN (SELECT table_schema, table_name FROM information_schema.statistics WHERE index_name = 'PRIMARY') AS B
ON A.table_schema = B.table_schema AND A.table_name = B.table_name
WHERE A.table_schema NOT IN ('information_schema' , 'mysql','performance_schema', 'sys')
AND A.table_type='BASE TABLE'
AND B.table_name IS NULL;
20、 查询非InnoDB表
--非innodb表
SELECT table_schema,table_name,engine FROM information_schema.tables where table_schema not in ('mysql','sys','information_schema','performance_schema') and engine!='InnoDB';
21、查询从库状态信息（主从状态，延迟）
--主从状态: (Slave_IO_Running和Slave_SQL_Running 都为YES 且Seconds_Behind_Master 为0)
show slave status\G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 10.120.184.82
Master_User: repuser
Master_Port: 3306
Connect_Retry: 5
Master_Log_File: mysql-bin.001026
Read_Master_Log_Pos: 182832
Relay_Log_File: mysql-relay-bin.002069
Relay_Log_Pos: 183005
Relay_Master_Log_File: mysql-bin.001026
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 182832
Relay_Log_Space: 183299
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 330682
Master_UUID: d2ba61a0-5b46-11ee-b627-005056b51543
Master_Info_File: mysql.slave_master_info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp:
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set: d2ba61a0-5b46-11ee-b627-005056b51543:12832492-14068377
Executed_Gtid_Set: a5bf5226-5b48-11ee-ae63-005056b53ab2:1,
d2ba61a0-5b46-11ee-b627-005056b51543:1-14068377
Auto_Position: 1
Replicate_Rewrite_DB:
Channel_Name:
Master_TLS_Version:
22、 查看慢日志信息：是否开启及慢日志的位置
--确认慢日志是否开启：slow_query_log为ON 及慢日志位置：/data/mysql8036/3306/logs/slow.log
root@localhost:sys 04:14:14 >show global variables like 'slow%';
+---------------------+------------------------------------+
| Variable_name | Value |
+---------------------+------------------------------------+
| slow_launch_time | 2 |
| slow_query_log | ON |
| slow_query_log_file | /data/mysql8036/3306/logs/slow.log |
+---------------------+------------------------------------+
3 rows in set (0.00 sec)
--确认慢日志记录的时间阈值：
root@localhost:sys 04:14:16 >show global variables like 'long%';
+-----------------+----------+
| Variable_name | Value |
+-----------------+----------+
| long_query_time | 1.000000 |
+-----------------+----------+
1 row in set (0.00 sec)
总结
以上这些命令是MySQL DBA在日常工作中经常使用的，可以帮助DBA监控数据库状态、管理用户权限、优化查询性能、查找关键信息等。在执行这些操作时，DBA需要根据实际情况和数据库的配置来做适当调整。
- 系统参数performance_schema一定要配置为ON
- 针对的是MySQL8.0版本
- 一些SQL最好带上库名
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