1. 概述
information_schema 数据库跟 performance_schema 一样，都是 MySQL 自带的信息数据库。其中 performance_schema 用于性能分析，而 information_schema 用于存储数据库元数据(关于数据的数据)，例如数据库名、表名、列的数据类型、访问权限等。
information_schema 中的表实际上是视图，而不是基本表，因此，文件系统上没有与之相关的文件。
(资料图)
mysql> use information_schema;Reading table information for completion of table and column namesYou can turn off this feature to get a quicker startup with -ADatabase changedmysql> 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 || OPTIMIZER_TRACE || 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_LOCKS || INNODB_TRX || INNODB_SYS_DATAFILES || INNODB_FT_CONFIG || INNODB_SYS_VIRTUAL || INNODB_CMP || INNODB_FT_BEING_DELETED || INNODB_CMP_RESET || INNODB_CMP_PER_INDEX || INNODB_CMPMEM_RESET || INNODB_FT_DELETED || INNODB_BUFFER_PAGE_LRU || INNODB_LOCK_WAITS || INNODB_TEMP_TABLE_INFO || INNODB_SYS_INDEXES || INNODB_SYS_TABLES || INNODB_SYS_FIELDS || INNODB_CMP_PER_INDEX_RESET || INNODB_BUFFER_PAGE || INNODB_FT_DEFAULT_STOPWORD || INNODB_FT_INDEX_TABLE || INNODB_FT_INDEX_CACHE || INNODB_SYS_TABLESPACES || INNODB_METRICS || INNODB_SYS_FOREIGN_COLS || INNODB_CMPMEM || INNODB_BUFFER_POOL_STATS || INNODB_SYS_COLUMNS || INNODB_SYS_FOREIGN || INNODB_SYS_TABLESTATS |+---------------------------------------+61 rows in set (0.00 sec)
2. information_schema 库中常用的表
CHARACTER_SETS 表
提供了 mysql 可用字符集的信息。SHOW CHARACTER SET; 命令从这个表获取结果。
mysql> SHOW CHARACTER SET;+----------+---------------------------------+---------------------+--------+| Charset | Description | Default collation | Maxlen |+----------+---------------------------------+---------------------+--------+| big5 | Big5 Traditional Chinese | big5_chinese_ci | 2 || dec8 | DEC West European | dec8_swedish_ci | 1 || cp850 | DOS West European | cp850_general_ci | 1 |...| eucjpms | UJIS for Windows Japanese | eucjpms_japanese_ci | 3 || gb18030 | China National Standard GB18030 | gb18030_chinese_ci | 4 |+----------+---------------------------------+---------------------+--------+41 rows in set (0.07 sec)mysql> SELECT * FROM CHARACTER_SETS;+--------------------+----------------------+---------------------------------+--------+| CHARACTER_SET_NAME | DEFAULT_COLLATE_NAME | DESCRIPTION | MAXLEN |+--------------------+----------------------+---------------------------------+--------+| big5 | big5_chinese_ci | Big5 Traditional Chinese | 2 || dec8 | dec8_swedish_ci | DEC West European | 1 || cp850 | cp850_general_ci | DOS West European | 1 |...| eucjpms | eucjpms_japanese_ci | UJIS for Windows Japanese | 3 || gb18030 | gb18030_chinese_ci | China National Standard GB18030 | 4 |+--------------------+----------------------+---------------------------------+--------+41 rows in set (0.00 sec)
SCHEMATA 表
当前 mysql 实例中所有数据库的信息。SHOW DATABASES; 命令从这个表获取数据。
mysql> SELECT * FROM SCHEMATA;+--------------+--------------------+----------------------------+------------------------+----------+| CATALOG_NAME | SCHEMA_NAME | DEFAULT_CHARACTER_SET_NAME | DEFAULT_COLLATION_NAME | SQL_PATH |+--------------+--------------------+----------------------------+------------------------+----------+| def | information_schema | utf8 | utf8_general_ci | NULL || def | mysql | latin1 | latin1_swedish_ci | NULL || def | performance_schema | utf8 | utf8_general_ci | NULL || def | sys | utf8 | utf8_general_ci | NULL || def | test | utf8 | utf8_unicode_ci | NULL |+--------------+--------------------+----------------------------+------------------------+----------+10 rows in set (0.00 sec)mysql> show databases;+--------------------+| Database |+--------------------+| information_schema || mysql || performance_schema || sys || test |+--------------------+10 rows in set (0.00 sec)
TABLES 表
存储数据库中的表信息（包括视图），包括表属于哪个数据库，表的类型、存储引擎、创建时间等信息。SHOW TABLES FROM XX; 命令从这个表获取结果。
mysql> SELECT * FROM TABLES;+---------------+--------------------+------------------------------------------------------+-------------+--------------------+---------+------------+------------+----------------+-------------+--------------------+--------------+-----------+----------------+---------------------+---------------------+---------------------+-------------------+----------+--------------------+--------------------------------------------+| TABLE_CATALOG | TABLE_SCHEMA | TABLE_NAME | TABLE_TYPE | ENGINE | VERSION | ROW_FORMAT | TABLE_ROWS | AVG_ROW_LENGTH | DATA_LENGTH | MAX_DATA_LENGTH | INDEX_LENGTH | DATA_FREE | AUTO_INCREMENT | CREATE_TIME | UPDATE_TIME | CHECK_TIME | TABLE_COLLATION | CHECKSUM | CREATE_OPTIONS | TABLE_COMMENT |+---------------+--------------------+------------------------------------------------------+-------------+--------------------+---------+------------+------------+----------------+-------------+--------------------+--------------+-----------+----------------+---------------------+---------------------+---------------------+-------------------+----------+--------------------+--------------------------------------------+| def | information_schema | CHARACTER_SETS | SYSTEM VIEW | MEMORY | 10 | Fixed | NULL | 384 | 0 | 16434816 | 0 | 0 | NULL | 2018-04-23 11:51:32 | NULL | NULL | utf8_general_ci | NULL | max_rows=43690 | || def | information_schema | COLLATIONS | SYSTEM VIEW | MEMORY | 10 | Fixed | NULL | 231 | 0 | 16704765 | 0 | 0 | NULL | 2018-04-23 11:51:32 | NULL | NULL | utf8_general_ci | NULL | max_rows=72628 | |...| def | zentao | zt_usertpl | BASE TABLE | MyISAM | 10 | Dynamic | 0 | 0 | 0 | 281474976710655 | 1024 | 0 | 1 | 2017-08-16 16:36:45 | 2017-08-16 16:36:45 | NULL | utf8_general_ci | NULL | | |+---------------+--------------------+------------------------------------------------------+-------------+--------------------+---------+------------+------------+----------------+-------------+--------------------+--------------+-----------+----------------+---------------------+---------------------+---------------------+-------------------+----------+--------------------+--------------------------------------------+525 rows in set (3.03 sec)mysql> SHOW TABLES FROM zentao;+-------------------+| Tables_in_zentao |+-------------------+| zt_action || zt_block || zt_branch |...| zt_usertpl |+-------------------+48 rows in set (0.00 sec)
COLUMNS 表
存储表中的列信息，包括表有多少列、每个列的类型等。SHOW COLUMNS FROM schemaname.tablename 命令从这个表获取结果。
mysql> SELECT * FROM COLUMNS LIMIT 2,5;+---------------+--------------------+----------------+--------------------+------------------+----------------+-------------+-----------+--------------------------+------------------------+-------------------+---------------+--------------------+--------------------+-----------------+-------------+------------+-------+------------+----------------+-----------------------+| TABLE_CATALOG | TABLE_SCHEMA | TABLE_NAME | COLUMN_NAME | ORDINAL_POSITION | COLUMN_DEFAULT | IS_NULLABLE | DATA_TYPE | CHARACTER_MAXIMUM_LENGTH | CHARACTER_OCTET_LENGTH | NUMERIC_PRECISION | NUMERIC_SCALE | DATETIME_PRECISION | CHARACTER_SET_NAME | COLLATION_NAME | COLUMN_TYPE | COLUMN_KEY | EXTRA | PRIVILEGES | COLUMN_COMMENT | GENERATION_EXPRESSION |+---------------+--------------------+----------------+--------------------+------------------+----------------+-------------+-----------+--------------------------+------------------------+-------------------+---------------+--------------------+--------------------+-----------------+-------------+------------+-------+------------+----------------+-----------------------+| def | information_schema | CHARACTER_SETS | DESCRIPTION | 3 | | NO | varchar | 60 | 180 | NULL | NULL | NULL | utf8 | utf8_general_ci | varchar(60) | | | select | | || def | information_schema | CHARACTER_SETS | MAXLEN | 4 | 0 | NO | bigint | NULL | NULL | 19 | 0 | NULL | NULL | NULL | bigint(3) | | | select | | || def | information_schema | COLLATIONS | COLLATION_NAME | 1 | | NO | varchar | 32 | 96 | NULL | NULL | NULL | utf8 | utf8_general_ci | varchar(32) | | | select | | || def | information_schema | COLLATIONS | CHARACTER_SET_NAME | 2 | | NO | varchar | 32 | 96 | NULL | NULL | NULL | utf8 | utf8_general_ci | varchar(32) | | | select | | || def | information_schema | COLLATIONS | ID | 3 | 0 | NO | bigint | NULL | NULL | 19 | 0 | NULL | NULL | NULL | bigint(11) | | | select | | |+---------------+--------------------+----------------+--------------------+------------------+----------------+-------------+-----------+--------------------------+------------------------+-------------------+---------------+--------------------+--------------------+-----------------+-------------+------------+-------+------------+----------------+-----------------------+5 rows in set (0.08 sec)
STATISTICS 表
表索引的信息。SHOW INDEX FROM schemaname.tablename; 命令从这个表获取结果。
mysql> SHOW INDEX FROM szhuizhong.users;+-------+------------+---------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |+-------+------------+---------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+| users | 0 | PRIMARY | 1 | UserID | A | 1460 | NULL | NULL | | BTREE | | || users | 0 | Account_index | 1 | Account | A | 1460 | NULL | NULL | | BTREE | | || users | 1 | CorpID | 1 | FromID | A | 2 | NULL | NULL | YES | BTREE | | |+-------+------------+---------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+3 rows in set (0.00 sec)
USER_PRIVILEGES 表
用户权限表。内容源自 mysql.user 授权表。是非标准表。
mysql> SELECT * FROM USER_PRIVILEGES;+-------------------------+---------------+-------------------------+--------------+| GRANTEE | TABLE_CATALOG | PRIVILEGE_TYPE | IS_GRANTABLE |+-------------------------+---------------+-------------------------+--------------+| "mysql.sys"@"localhost" | def | USAGE | NO || "root"@"%" | def | SELECT | YES || "root"@"%" | def | INSERT | YES || "root"@"%" | def | UPDATE | YES || "root"@"%" | def | DELETE | YES || "root"@"%" | def | CREATE | YES || "root"@"%" | def | DROP | YES || "root"@"%" | def | RELOAD | YES || "root"@"%" | def | SHUTDOWN | YES || "root"@"%" | def | PROCESS | YES || "root"@"%" | def | FILE | YES || "root"@"%" | def | REFERENCES | YES || "root"@"%" | def | INDEX | YES || "root"@"%" | def | ALTER | YES || "root"@"%" | def | SHOW DATABASES | YES || "root"@"%" | def | SUPER | YES || "root"@"%" | def | CREATE TEMPORARY TABLES | YES || "root"@"%" | def | LOCK TABLES | YES || "root"@"%" | def | EXECUTE | YES || "root"@"%" | def | REPLICATION SLAVE | YES || "root"@"%" | def | REPLICATION CLIENT | YES || "root"@"%" | def | CREATE VIEW | YES || "root"@"%" | def | SHOW VIEW | YES || "root"@"%" | def | CREATE ROUTINE | YES || "root"@"%" | def | ALTER ROUTINE | YES || "root"@"%" | def | CREATE USER | YES || "root"@"%" | def | EVENT | YES || "root"@"%" | def | TRIGGER | YES || "root"@"%" | def | CREATE TABLESPACE | YES |+-------------------------+---------------+-------------------------+--------------+29 rows in set (0.00 sec)
SCHEMA_PRIVILEGES 表
方案权限表。给出了关于方案（数据库）权限的信息。内容来自 mysql.db 授权表。是非标准表。
mysql> SELECT * FROM SCHEMA_PRIVILEGES;+-------------------------+---------------+--------------+-------------------------+--------------+| GRANTEE | TABLE_CATALOG | TABLE_SCHEMA | PRIVILEGE_TYPE | IS_GRANTABLE |+-------------------------+---------------+--------------+-------------------------+--------------+| "mysql.sys"@"localhost" | def | sys | TRIGGER | NO || "root"@"%" | def | mysql | SELECT | YES || "root"@"%" | def | mysql | INSERT | YES || "root"@"%" | def | mysql | UPDATE | YES || "root"@"%" | def | mysql | DELETE | YES || "root"@"%" | def | mysql | CREATE | YES || "root"@"%" | def | mysql | DROP | YES || "root"@"%" | def | mysql | REFERENCES | YES || "root"@"%" | def | mysql | INDEX | YES || "root"@"%" | def | mysql | ALTER | YES || "root"@"%" | def | mysql | CREATE TEMPORARY TABLES | YES || "root"@"%" | def | mysql | LOCK TABLES | YES || "root"@"%" | def | mysql | EXECUTE | YES || "root"@"%" | def | mysql | CREATE VIEW | YES || "root"@"%" | def | mysql | SHOW VIEW | YES || "root"@"%" | def | mysql | CREATE ROUTINE | YES || "root"@"%" | def | mysql | ALTER ROUTINE | YES || "root"@"%" | def | mysql | EVENT | YES || "root"@"%" | def | mysql | TRIGGER | YES |+-------------------------+---------------+--------------+-------------------------+--------------+19 rows in set (0.00 sec)
TABLE_PRIVILEGES 表
表权限表。给出了关于表权限的信息。内容源自 mysql.tables_priv 授权表。是非标准表。
mysql> SELECT * FROM TABLE_PRIVILEGES;+-------------------------+---------------+--------------+------------+----------------+--------------+| GRANTEE | TABLE_CATALOG | TABLE_SCHEMA | TABLE_NAME | PRIVILEGE_TYPE | IS_GRANTABLE |+-------------------------+---------------+--------------+------------+----------------+--------------+| "mysql.sys"@"localhost" | def | sys | sys_config | SELECT | NO |+-------------------------+---------------+--------------+------------+----------------+--------------+1 row in set (0.00 sec)
COLUMN_PRIVILEGES 表
列权限表。给出了关于列权限的信息。内容源自 mysql.columns_priv 授权表。是非标准表。
mysql> SELECT * FROM COLUMN_PRIVILEGES;Empty set (0.00 sec)
COLLATIONS 表
提供了关于各字符集的对照信息。SHOW COLLATION; 命令从这个表获取结果。
mysql> SELECT * FROM COLLATIONS;+--------------------------+--------------------+-----+------------+-------------+---------+| COLLATION_NAME | CHARACTER_SET_NAME | ID | IS_DEFAULT | IS_COMPILED | SORTLEN |+--------------------------+--------------------+-----+------------+-------------+---------+| big5_chinese_ci | big5 | 1 | Yes | Yes | 1 || big5_bin | big5 | 84 | | Yes | 1 || dec8_swedish_ci | dec8 | 3 | Yes | Yes | 1 || dec8_bin | dec8 | 69 | | Yes | 1 |...| gb18030_bin | gb18030 | 249 | | Yes | 1 || gb18030_unicode_520_ci | gb18030 | 250 | | Yes | 8 |+--------------------------+--------------------+-----+------------+-------------+---------+222 rows in set (0.03 sec)
COLLATION_CHARACTER_SET_APPLICABILITY 表
指明了可用于校对的字符集。相当于 SHOW COLLATION 命令结果的前两个字段。
mysql> SELECT * FROM COLLATION_CHARACTER_SET_APPLICABILITY;+--------------------------+--------------------+| COLLATION_NAME | CHARACTER_SET_NAME |+--------------------------+--------------------+| big5_chinese_ci | big5 || big5_bin | big5 || dec8_swedish_ci | dec8 |...| gb18030_bin | gb18030 || gb18030_unicode_520_ci | gb18030 |+--------------------------+--------------------+222 rows in set (0.00 sec)
TABLE_CONSTRAINTS 表
描述了存在约束的表。以及表的约束类型。
mysql> SELECT * FROM TABLE_CONSTRAINTS;+--------------------+-------------------+--------------------+--------------+---------------------------+-----------------+| CONSTRAINT_CATALOG | CONSTRAINT_SCHEMA | CONSTRAINT_NAME | TABLE_SCHEMA | TABLE_NAME | CONSTRAINT_TYPE |+--------------------+-------------------+--------------------+--------------+---------------------------+-----------------+| def | mysql | PRIMARY | mysql | columns_priv | PRIMARY KEY || def | mysql | PRIMARY | mysql | db | PRIMARY KEY || def | mysql | PRIMARY | mysql | engine_cost | PRIMARY KEY || def | mysql | PRIMARY | mysql | event | PRIMARY KEY || def | mysql | PRIMARY | mysql | func | PRIMARY KEY || def | mysql | PRIMARY | mysql | gtid_executed | PRIMARY KEY || def | mysql | PRIMARY | mysql | help_category | PRIMARY KEY || def | mysql | name | mysql | help_category | UNIQUE || def | mysql | PRIMARY | mysql | help_keyword | PRIMARY KEY || def | mysql | name | mysql | help_keyword | UNIQUE || def | mysql | PRIMARY | mysql | help_relation | PRIMARY KEY || def | mysql | PRIMARY | mysql | help_topic | PRIMARY KEY || def | mysql | name | mysql | help_topic | UNIQUE || def | mysql | PRIMARY | mysql | innodb_index_stats | PRIMARY KEY || def | mysql | PRIMARY | mysql | innodb_table_stats | PRIMARY KEY || def | mysql | PRIMARY | mysql | ndb_binlog_index | PRIMARY KEY || def | mysql | PRIMARY | mysql | plugin | PRIMARY KEY || def | mysql | PRIMARY | mysql | proc | PRIMARY KEY || def | mysql | PRIMARY | mysql | procs_priv | PRIMARY KEY || def | mysql | PRIMARY | mysql | proxies_priv | PRIMARY KEY || def | mysql | PRIMARY | mysql | server_cost | PRIMARY KEY || def | mysql | PRIMARY | mysql | servers | PRIMARY KEY || def | mysql | PRIMARY | mysql | slave_master_info | PRIMARY KEY || def | mysql | PRIMARY | mysql | slave_relay_log_info | PRIMARY KEY || def | mysql | PRIMARY | mysql | slave_worker_info | PRIMARY KEY || def | mysql | PRIMARY | mysql | tables_priv | PRIMARY KEY || def | mysql | PRIMARY | mysql | time_zone | PRIMARY KEY || def | mysql | PRIMARY | mysql | time_zone_leap_second | PRIMARY KEY || def | mysql | PRIMARY | mysql | time_zone_name | PRIMARY KEY || def | mysql | PRIMARY | mysql | time_zone_transition | PRIMARY KEY || def | mysql | PRIMARY | mysql | time_zone_transition_type | PRIMARY KEY || def | mysql | PRIMARY | mysql | user | PRIMARY KEY || def | sys | PRIMARY | sys | sys_config | PRIMARY KEY || def | zentao | PRIMARY | zentao | zt_action | PRIMARY KEY |...| def | zentao | account | zentao | zt_usergroup | UNIQUE || def | zentao | PRIMARY | zentao | zt_userquery | PRIMARY KEY || def | zentao | PRIMARY | zentao | zt_usertpl | PRIMARY KEY |+--------------------+-------------------+--------------------+--------------+---------------------------+-----------------+213 rows in set (0.37 sec)
KEY_COLUMN_USAGE 表
描述了具有约束的键列。
mysql> SELECT * FROM KEY_COLUMN_USAGE;+--------------------+-------------------+--------------------+---------------+--------------+---------------------------+--------------------+------------------+-------------------------------+-------------------------+-----------------------+------------------------+| CONSTRAINT_CATALOG | CONSTRAINT_SCHEMA | CONSTRAINT_NAME | TABLE_CATALOG | TABLE_SCHEMA | TABLE_NAME | COLUMN_NAME | ORDINAL_POSITION | POSITION_IN_UNIQUE_CONSTRAINT | REFERENCED_TABLE_SCHEMA | REFERENCED_TABLE_NAME | REFERENCED_COLUMN_NAME |+--------------------+-------------------+--------------------+---------------+--------------+---------------------------+--------------------+------------------+-------------------------------+-------------------------+-----------------------+------------------------+| def | mysql | PRIMARY | def | mysql | columns_priv | Host | 1 | NULL | NULL | NULL | NULL || def | mysql | PRIMARY | def | mysql | columns_priv | Db | 2 | NULL | NULL | NULL | NULL || def | mysql | PRIMARY | def | mysql | columns_priv | User | 3 | NULL | NULL | NULL | NULL || def | mysql | PRIMARY | def | mysql | columns_priv | Table_name | 4 | NULL | NULL | NULL | NULL || def | mysql | PRIMARY | def | mysql | columns_priv | Column_name | 5 | NULL | NULL | NULL | NULL |...| def | mysql | PRIMARY | def | mysql | time_zone_leap_second | Transition_time | 1 | NULL | NULL | NULL | NULL || def | mysql | PRIMARY | def | mysql | time_zone_name | Name | 1 | NULL | NULL | NULL | NULL || def | mysql | PRIMARY | def | mysql | time_zone_transition | Time_zone_id | 1 | NULL | NULL | NULL | NULL || def | mysql | PRIMARY | def | mysql | time_zone_transition | Transition_time | 2 | NULL | NULL | NULL | NULL || def | mysql | PRIMARY | def | mysql | time_zone_transition_type | Time_zone_id | 1 | NULL | NULL | NULL | NULL || def | mysql | PRIMARY | def | mysql | time_zone_transition_type | Transition_type_id | 2 | NULL | NULL | NULL | NULL || def | mysql | PRIMARY | def | mysql | user | Host | 1 | NULL | NULL | NULL | NULL || def | mysql | PRIMARY | def | mysql | user | User | 2 | NULL | NULL | NULL | NULL || def | sys | PRIMARY | def | sys | sys_config | variable | 1 | NULL | NULL | NULL | NULL |+--------------------+-------------------+--------------------+---------------+--------------+---------------------------+--------------------+------------------+-------------------------------+-------------------------+-----------------------+------------------------+278 rows in set (0.03 sec)
ROUTINES 表
提供了关于存储子程序（存储程序和函数）的信息。此时，ROUTINES 表不包含自定义函数（UDF）。名为“mysql.proc name”的列指明了对应于 INFORMATION_SCHEMA.ROUTINES 表的 mysql.proc 列。
VIEWS 表
给出了关于数据库中的视图的信息。需要有 show views 权限，否则无法查看视图信息。
mysql> SELECT * FROM VIEWS LIMIT 1\G*************************** 1. row *************************** TABLE_CATALOG: def TABLE_SCHEMA: sys TABLE_NAME: host_summary VIEW_DEFINITION: select if(isnull(`performance_schema`.`accounts`.`HOST`),"background",`performance_schema`.`accounts`.`HOST`) AS `host`,sum(`stmt`.`total`) AS `statements`,`sys`.`format_time`(sum(`stmt`.`total_latency`)) AS `statement_latency`,`sys`.`format_time`(ifnull((sum(`stmt`.`total_latency`) / nullif(sum(`stmt`.`total`),0)),0)) AS `statement_avg_latency`,sum(`stmt`.`full_scans`) AS `table_scans`,sum(`io`.`ios`) AS `file_ios`,`sys`.`format_time`(sum(`io`.`io_latency`)) AS `file_io_latency`,sum(`performance_schema`.`accounts`.`CURRENT_CONNECTIONS`) AS `current_connections`,sum(`performance_schema`.`accounts`.`TOTAL_CONNECTIONS`) AS `total_connections`,count(distinct `performance_schema`.`accounts`.`USER`) AS `unique_users`,`sys`.`format_bytes`(sum(`mem`.`current_allocated`)) AS `current_memory`,`sys`.`format_bytes`(sum(`mem`.`total_allocated`)) AS `total_memory_allocated` from (((`performance_schema`.`accounts` join `sys`.`x$host_summary_by_statement_latency` `stmt` on((`performance_schema`.`accounts`.`HOST` = `stmt`.`host`))) join `sys`.`x$host_summary_by_file_io` `io` on((`performance_schema`.`accounts`.`HOST` = `io`.`host`))) join `sys`.`x$memory_by_host_by_current_bytes` `mem` on((`performance_schema`.`accounts`.`HOST` = `mem`.`host`))) group by if(isnull(`performance_schema`.`accounts`.`HOST`),"background",`performance_schema`.`accounts`.`HOST`) CHECK_OPTION: NONE IS_UPDATABLE: NO DEFINER: mysql.sys@localhost SECURITY_TYPE: INVOKERCHARACTER_SET_CLIENT: utf8COLLATION_CONNECTION: utf8_general_ci1 row in set (0.03 sec)
TRIGGERS 表
提供了关于触发程序的信息。必须有 super 权限才能查看该表。
mysql> SELECT * FROM TRIGGERS LIMIT 1\G*************************** 1. row *************************** TRIGGER_CATALOG: def TRIGGER_SCHEMA: sys TRIGGER_NAME: sys_config_insert_set_user EVENT_MANIPULATION: INSERT EVENT_OBJECT_CATALOG: def EVENT_OBJECT_SCHEMA: sys EVENT_OBJECT_TABLE: sys_config ACTION_ORDER: 1 ACTION_CONDITION: NULL ACTION_STATEMENT: BEGIN IF @sys.ignore_sys_config_triggers != true AND NEW.set_by IS NULL THEN SET NEW.set_by = USER(); END IF; END ACTION_ORIENTATION: ROW ACTION_TIMING: BEFOREACTION_REFERENCE_OLD_TABLE: NULLACTION_REFERENCE_NEW_TABLE: NULL ACTION_REFERENCE_OLD_ROW: OLD ACTION_REFERENCE_NEW_ROW: NEW CREATED: 2017-05-27 11:18:43.60 SQL_MODE: DEFINER: mysql.sys@localhost CHARACTER_SET_CLIENT: utf8 COLLATION_CONNECTION: utf8_general_ci DATABASE_COLLATION: utf8_general_ci1 row in set (0.00 sec)
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