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information_schema模式表介绍processlist
在mysql里，我们一般通过show （full）processlist查看当前连接情况，处理各种数据库问题。现在在information_schema模式下，5.5以后增加了processlist表，里面存储了当前连接信息，跟show (full) processlist存储的一样。通过processlist 我们可以统计分析一些信息，而不依赖于shell命令（如 grep、awk等）
如 查询当前ip的连接信息
mysql> select substring_index(host,':',1),count(*) from processlist group by substring_index(host,':',1);
同时，还增加了对innodb存储引擎性能信息等相关表，如下以innodb开头的表
mysql> select database();
+--------------------+
| database() |
+--------------------+
| information_schema |
+--------------------+
1 row in set (0.00 sec)
mysql> show tables;
+---------------------------------------+
| Tables_in_information_schema |
+---------------------------------------+
| CHARACTER_SETS |
| COLLATIONS |
| COLLATION_CHARACTER_SET_APPLICABILITY |
| COLUMNS |
| COLUMN_PRIVILEGES |
| ENGINES |
| EVENTS |
| FILES |
| GLOBAL_STATUS |
| GLOBAL_VARIABLES |
| KEY_COLUMN_USAGE |
| PARAMETERS |
| PARTITIONS |
| PLUGINS |
| PROCESSLIST |
| PROFILING |
| REFERENTIAL_CONSTRAINTS |
| ROUTINES |
| SCHEMATA |
| SCHEMA_PRIVILEGES |
| SESSION_STATUS |
| SESSION_VARIABLES |
| STATISTICS |
| TABLES |
| TABLESPACES |
| TABLE_CONSTRAINTS |
| TABLE_PRIVILEGES |
| TRIGGERS |
| USER_PRIVILEGES |
| VIEWS |
| INNODB_BUFFER_PAGE |
| INNODB_TRX |
| INNODB_BUFFER_POOL_STATS |
| INNODB_LOCK_WAITS |
| INNODB_CMPMEM |
| INNODB_CMP |
| INNODB_LOCKS |
| INNODB_CMPMEM_RESET |
| INNODB_CMP_RESET |
| INNODB_BUFFER_PAGE_LRU |
+---------------------------------------+
40 rows in set (0.01 sec)
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