MySql常用命令--优化参数以及日常管理 -借用

• 显示插入查询的优化参数：

show variables like "concurrent_insert";
+-------------------+-------+ | Variable_name     | Value |
+-------------------+-------+ | concurrent_insert | AUTO  |
+-------------------+-------+ set GLOBAL concurrent_insert=2;

• 插入数据时MySQL会对插入的记录进行唯一性校验
  这种校验也会降低插入记录的速度。可以在插入记录之前禁用唯一性检查。等到记录插入完毕后再开启。禁用唯一性检查的语句如下：

SET UNIQUE_CHECKS=0;

	
	

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重新开启唯一性检查的语句如下：

SET UNIQUE_CHECKS=1;

	
	

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mysql> show variables like "UNIQUE_CHECKS";
+---------------+-------+ | Variable_name | Value |
+---------------+-------+ | unique_checks | ON    |
+---------------+-------+

• mysql设置最大连接数量

mysql> set GLOBAL max_connections = 1000;
Query OK, 0 rows affected (0.00 sec)

• 之前配置了mysql的主从备份
  结果发现日志很多，占据了很多的磁盘空间，需要进行额外的磁盘管理
  进入mysql的存储区域，查看一下数据部分的空间大小

/mnt/ssd/data$ ls
auto.cnf          mysql-bin.000139 mysql-bin.000149 mysql-bin.000159 mysql-bin.000169 mysql-bin.000179 mysql-bin.000189 mysql-bin.000199 mysql-bin.000209 mysql-bin.index
db_user_msg       mysql-bin.000140 mysql-bin.000150 mysql-bin.000160 mysql-bin.000170 mysql-bin.000180 mysql-bin.000190 mysql-bin.000200 mysql-bin.000210 performance_schema
ibdata1           mysql-bin.000141 mysql-bin.000151 mysql-bin.000161 mysql-bin.000171 mysql-bin.000181 mysql-bin.000191 mysql-bin.000201 mysql-bin.000211 StockData
ib_logfile0       mysql-bin.000142 mysql-bin.000152 mysql-bin.000162 mysql-bin.000172 mysql-bin.000182 mysql-bin.000192 mysql-bin.000202 mysql-bin.000212 ib_logfile1       mysql-bin.000143 mysql-bin.000153 mysql-bin.000163 mysql-bin.000173 mysql-bin.000183 mysql-bin.000193 mysql-bin.000203 mysql-bin.000213 mysql             mysql-bin.000144 mysql-bin.000154 mysql-bin.000164 mysql-bin.000174 mysql-bin.000184 mysql-bin.000194 mysql-bin.000204 mysql-bin.000214 mysql-bin.000135 mysql-bin.000145 mysql-bin.000155 mysql-bin.000165 mysql-bin.000175 mysql-bin.000185 mysql-bin.000195 mysql-bin.000205 mysql-bin.000215 mysql-bin.000136 mysql-bin.000146 mysql-bin.000156 mysql-bin.000166 mysql-bin.000176 mysql-bin.000186 mysql-bin.000196 mysql-bin.000206 mysql-bin.000216 mysql-bin.000137 mysql-bin.000147 mysql-bin.000157 mysql-bin.000167 mysql-bin.000177 mysql-bin.000187 mysql-bin.000197 mysql-bin.000207 mysql-bin.000217 mysql-bin.000138 mysql-bin.000148 mysql-bin.000158 mysql-bin.000168 mysql-bin.000178 mysql-bin.000188 mysql-bin.000198 mysql-bin.000208 mysql-bin.000218

	
	

		显示mysql中数据部分和基本的配置部分所占用的磁盘空间
	

/mnt/ssd/data$ sudo du -h -d 1 163G ./StockData 636K ./performance_schema 1.7M ./mysql 56K ./db_user_msg 242G .

结果发现这其中很多的空间都被mysql-bin*文件所占用了

/mnt/ssd/data$ sudo du -c -h mysql-bin* 1.1G    mysql-bin.000135 ...... 491M    mysql-bin.000218 4.0K    mysql-bin.index 80G     total
结果显示mysql-bin占用了大约80G的磁盘空间

现在我们要将这些日志清理掉

mysql> show master logs;
+------------------+------------+ | Log_name         | File_size  |
+------------------+------------+ | mysql-bin.000135 | 1073742116 |
| mysql-bin.000136 | 1073742153 | ......
| mysql-bin.000216 | 1073747783 |
| mysql-bin.000217 | 1073742128 |
| mysql-bin.000218 |  514734902 |
+------------------+------------+
84 rows in set (0.01 sec)
这应该是主从备份一周以内的日志文件

查看一下目前正在起作用的日志文件是哪一个
mysql> show master status;
+------------------+-----------+--------------+------------------+-------------------+
| File             | Position  | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+-----------+--------------+------------------+-------------------+
| mysql-bin.000218 | 514734902 |              |                  |                   |
+------------------+-----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

• 如何删除多余的日志
  日志的删除
  对于比较繁忙的OLTP系统，由于每天生产日志量大，这些日志如果长时间不清理，将会对磁盘空间带来很大的浪费，因此，定期删除日志是DBA维护Mysql数据库的一个重要工作内容，下面将介绍几种删除日志的常见方法:

先去获得mysql中数据存储的位置：

mysql> show variables like "datadir";
+---------------+-----------------+ | Variable_name | Value           |
+---------------+-----------------+ | datadir       | /var/lib/mysql/ |
+---------------+-----------------+ 1 row in set (0.00 sec)
这是mysql中的默认存储位置

再去查看master中日志的存储位置：

mysql> show variables like "log%";
+----------------------------------------+-------------------------------+
| Variable_name | Value |
+----------------------------------------+-------------------------------+ | log_bin                                | ON | | log_bin_basename                       | /mnt/ssd/data/mysql-bin       | | log_bin_index                          | /mnt/ssd/data/mysql-bin.index | | log_bin_trust_function_creators        | OFF | | log_bin_use_v1_row_events              | OFF | | log_error                              | /var/log/mysql/error.log      | | log_output                             | FILE | | log_queries_not_using_indexes          | OFF | | log_slave_updates                      | OFF | | log_slow_admin_statements              | OFF | | log_slow_slave_statements              | OFF | | log_throttle_queries_not_using_indexes | 0 | | log_warnings                           | 1 |
+----------------------------------------+-------------------------------+ 13 rows in set (0.00 sec)

	
	

		查询slave节点的更新状态：
	

mysql> show slave status \G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event
                  Master_Host: 25.25.2.6 Master_User: gpx_sync
                  Master_Port: 3306 Connect_Retry: 10 Master_Log_File: mysql-bin.000218 Read_Master_Log_Pos: 514734902 Relay_Log_File: mysqld-relay-bin.000669 Relay_Log_Pos: 236 Relay_Master_Log_File: mysql-bin.000218 Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
              Replicate_Do_DB:
          Replicate_Ignore_DB:
           Replicate_Do_Table: StockData.t_day_stock
       Replicate_Ignore_Table:
      Replicate_Wild_Do_Table:
  Replicate_Wild_Ignore_Table:
                   Last_Errno: 0 Last_Error:
                 Skip_Counter: 0 Exec_Master_Log_Pos: 514734902 Relay_Log_Space: 132818854 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: 1 Master_UUID: e61e54d8-1e08-11e5-9160-44a842112d25
             Master_Info_File: /var/lib/mysql/master.info
                    SQL_Delay: 0 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: Slave has read all relay log; waiting for the slave I/O thread to update it
           Master_Retry_Count: 86400 Master_Bind:
      Last_IO_Error_Timestamp:
     Last_SQL_Error_Timestamp:
               Master_SSL_Crl:
           Master_SSL_Crlpath:
           Retrieved_Gtid_Set:
            Executed_Gtid_Set:
                Auto_Position: 0 1 row in set (0.00 sec)

这里面我们获得的有用的信息是：
              Master_Log_File: mysql-bin.000218 Read_Master_Log_Pos: 514734902 Relay_Log_File: mysqld-relay-bin.000669 Relay_Log_Pos: 236 Relay_Master_Log_File: mysql-bin.000218 Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
      Slave_SQL_Running_State: Slave has read all relay log; waiting for the slave I/O thread to update it

	
	

		执行“reset master;”命令，该命令将删除所有二进制日志，新日志的编号从“000001” 开始；
	

Mysql>reset master;

	
	

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1. 执行“Purge master logs to ‘mysql-bin.’” 命令，该命令将删除“” 编号之前的所有日志，下列中删除了“mysql-bin.000001”之前编号的所有日志;

Mysql>purge master logs to 'mysql-bin.000215';

	
	

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1. 执行“purge master logs before ‘yyyy-mm-dd hh24:min:ss’”命令，该命令将删除日期为“yyyy-mm-dd hh24:mi:ss”之前产生的所有日志，下列中删除了日期在“2010-05-22 01:00:00”之前的所有日志

Mysql>purge master logs before ‘2010-05-22 01:00:00’;

	
	

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1. 设置参数 –expire_logs_days=#(days)，此参数的含义是设置日志的过期天数，过来指定的天数后日志将会被自动删除，这样将有利于减少DBA管理日志的工作量。

gpx@dell:~$ sudo vim /etc/mysql/my.cnf [mysqld] expire_logs_days = 3
这样，3天前的日志都会被删除，系统自动删除

查看系统中对于二进制日志自动删除的过期时间 mysql> show variables like "expire%";
+------------------+-------+ | Variable_name    | Value |
+------------------+-------+ | expire_logs_days | 3     |
+------------------+-------+ 1 row in set (0.00 sec)