author：彭程

介绍

在安装完mysql后，我们会发现里边已经自带了4个默认的数据库，不同的mysql版本自带的默认数据库不同，本文使用的mysql版本为8.0.26。四个数据库如下：

  • information_schema
  • performance_schema
  • mysql
  • sys

information_schema

information_schema是一个信息数据库，它保存了mysql所有数据库的信息，如有多少个数据库，各个数据库有哪些表，各个表中的字段是什么数据类型，各个表中有哪些索引，各个数据库要什么权限才能访问。
数据库内表如下：

  1. mysql> use information_schema
  2. Database changed
  3. mysql> show tables;
  4. +---------------------------------------+
  5. | Tables_in_information_schema          |
  6. +---------------------------------------+
  7. | ADMINISTRABLE_ROLE_AUTHORIZATIONS     |
  8. | APPLICABLE_ROLES                      |
  9. | CHARACTER_SETS                        |
  10. | CHECK_CONSTRAINTS                     |
  11. | COLLATION_CHARACTER_SET_APPLICABILITY |
  12. | COLLATIONS                            |
  13. | COLUMN_PRIVILEGES                     |
  14. | COLUMN_STATISTICS                     |
  15. | COLUMNS                               |
  16. | COLUMNS_EXTENSIONS                    |
  17. | ENABLED_ROLES                         |
  18. | ENGINES                               |
  19. | EVENTS                                |
  20. | FILES                                 |
  21. | INNODB_BUFFER_PAGE                    |
  22. | INNODB_BUFFER_PAGE_LRU                |
  23. | INNODB_BUFFER_POOL_STATS              |
  24. | INNODB_CACHED_INDEXES                 |
  25. | INNODB_CMP                            |
  26. | INNODB_CMP_PER_INDEX                  |
  27. | INNODB_CMP_PER_INDEX_RESET            |
  28. | INNODB_CMP_RESET                      |
  29. | INNODB_CMPMEM                         |
  30. | INNODB_CMPMEM_RESET                   |
  31. | INNODB_COLUMNS                        |
  32. | INNODB_DATAFILES                      |
  33. | INNODB_FIELDS                         |
  34. | INNODB_FOREIGN                        |
  35. | INNODB_FOREIGN_COLS                   |
  36. | INNODB_FT_BEING_DELETED               |
  37. | INNODB_FT_CONFIG                      |
  38. | INNODB_FT_DEFAULT_STOPWORD            |
  39. | INNODB_FT_DELETED                     |
  40. | INNODB_FT_INDEX_CACHE                 |
  41. | INNODB_FT_INDEX_TABLE                 |
  42. | INNODB_INDEXES                        |
  43. | INNODB_METRICS                        |
  44. | INNODB_SESSION_TEMP_TABLESPACES       |
  45. | INNODB_TABLES                         |
  46. | INNODB_TABLESPACES                    |
  47. | INNODB_TABLESPACES_BRIEF              |
  48. | INNODB_TABLESTATS                     |
  49. | INNODB_TEMP_TABLE_INFO                |
  50. | INNODB_TRX                            |
  51. | INNODB_VIRTUAL                        |
  52. | KEY_COLUMN_USAGE                      |
  53. | KEYWORDS                              |
  54. | OPTIMIZER_TRACE                       |
  55. | PARAMETERS                            |
  56. | PARTITIONS                            |
  57. | PLUGINS                               |
  58. | PROCESSLIST                           |
  59. | PROFILING                             |
  60. | REFERENTIAL_CONSTRAINTS               |
  61. | RESOURCE_GROUPS                       |
  62. | ROLE_COLUMN_GRANTS                    |
  63. | ROLE_ROUTINE_GRANTS                   |
  64. | ROLE_TABLE_GRANTS                     |
  65. | ROUTINES                              |
  66. | SCHEMA_PRIVILEGES                     |
  67. | SCHEMATA                              |
  68. | SCHEMATA_EXTENSIONS                   |
  69. | ST_GEOMETRY_COLUMNS                   |
  70. | ST_SPATIAL_REFERENCE_SYSTEMS          |
  71. | ST_UNITS_OF_MEASURE                   |
  72. | STATISTICS                            |
  73. | TABLE_CONSTRAINTS                     |
  74. | TABLE_CONSTRAINTS_EXTENSIONS          |
  75. | TABLE_PRIVILEGES                      |
  76. | TABLES                                |
  77. | TABLES_EXTENSIONS                     |
  78. | TABLESPACES                           |
  79. | TABLESPACES_EXTENSIONS                |
  80. | TRIGGERS                              |
  81. | USER_ATTRIBUTES                       |
  82. | USER_PRIVILEGES                       |
  83. | VIEW_ROUTINE_USAGE                    |
  84. | VIEW_TABLE_USAGE                      |
  85. | VIEWS                                 |
  86. +---------------------------------------+
  87. 79 rows in set (0.01 sec)

这些表主要可以分为以下五类：

  1. INFORMATION_SCHEMA General Tables 通用表

通用表具体信息可以查看官网介绍：https://dev.mysql.com/doc/refman/8.0/en/general-information-schema-tables.html，下面对一些表的内容做简要介绍：
COLLATIONS表：提供了关于各字符集的对照信息。
COLUMNS表提供关于表中列的信息。详细表述了某张表的所有列以及每个列的信息。是show columns from schemaname.tablename的结果取之此表。

  1. mysql> show columns from ddm_group;
  2. +---------------+--------------+------+-----+---------+-------+
  3. | Field         | Type         | Null | Key | Default | Extra |
  4. +---------------+--------------+------+-----+---------+-------+
  5. | ddm_group_id  | varchar(128) | NO   | PRI | NULL    |       |
  6. | uid           | varchar(45)  | YES  |     | NULL    |       |
  7. | group_name    | varchar(64)  | YES  |     | NULL    |       |
  8. | admin_user    | varchar(64)  | YES  |     | NULL    |       |
  9. | admin_pwd     | varchar(64)  | YES  |     | NULL    |       |
  10. | service_port  | int          | YES  |     | NULL    |       |
  11. | admin_port    | int          | YES  |     | NULL    |       |
  12. | mysql_charset | varchar(64)  | YES  |     | NULL    |       |
  13. | mysql_version | varchar(45)  | YES  |     | NULL    |       |
  14. | memo          | varchar(256) | YES  |     | NULL    |       |
  15. | gmt_create    | timestamp    | YES  |     | NULL    |       |
  16. | gmt_modify    | timestamp    | YES  |     | NULL    |       |
  17. | status        | varchar(45)  | YES  |     | NULL    |       |
  18. +---------------+--------------+------+-----+---------+-------+
  19. 13 rows in set (0.01 sec)

COLUMN_PRIVILEGES表提供关于列特权的信息。它从mysql.columns_priv系统表中获取它的值。
ENGINES表提供了存储引擎的信息。用于检查是否支持存储引擎或查看默认引擎。
EVENTS表提供了有关事件管理器的信息。
FILES表提供关于MySQL表空间数据存储的文件的信息。FILES表提供了关于InnoDB数据文件的信息。在NDB集群中，该表还提供了关于存储NDB集群磁盘数据表的文件的信息。
KEYWORDS表列出了MySQL考虑的关键字，并为每一个表明它是否被保留。保留关键字在某些情况下可能需要特殊处理，例如作为标识符使用的特殊引号。该表为应用程序提供了MySQL关键字信息的运行时来源。

  1. mysql> select * from keywords;
  2. +----------------------------------------+----------+
  3. | WORD                                   | RESERVED |
  4. +----------------------------------------+----------+
  5. | ACCESSIBLE                             |        1 |
  6. | ACCOUNT                                |        0 |
  7. | ACTION                                 |        0 |
  8. | ACTIVE                                 |        0 |
  9. | ADD                                    |        1 |
  10. | ADMIN                                  |        0 |
  11. | AFTER                                  |        0 |
  12. ...
  13. | X509                                   |        0 |
  14. | XA                                     |        0 |
  15. | XID                                    |        0 |
  16. | XML                                    |        0 |
  17. | XOR                                    |        1 |
  18. | YEAR                                   |        0 |
  19. | YEAR_MONTH                             |        1 |
  20. | ZEROFILL                               |        1 |
  21. | ZONE                                   |        0 |
  22. +----------------------------------------+----------+
  23. 738 rows in set (0.03 sec)

OPTIMIZER_TRACE表提供优化器跟踪语句时生成的信息。包括跟踪所使用的内存总量的限制。
PARAMETERS表提供关于存储例程(存储过程和存储函数)的参数的信息，以及关于存储函数的返回值的信息。PARAMETERS表不包括内置(本机)函数或可加载函数。
PARTITIONS表提供了关于表分区的信息。该表中的每一行对应于分区表的一个单独分区或子分区。

  1. mysql> select * from partitions;
  2. +---------------+--------------------+------------------------------------------------------+----------------+-------------------+----------------------------+-------------------------------+------------------+---------------------+----------------------+-------------------------+-----------------------+------------+----------------+-------------+-----------------+--------------+-----------+---------------------+---------------------+------------+----------+-------------------+-----------+-----------------+
  3. | TABLE_CATALOG | TABLE_SCHEMA       | TABLE_NAME                                           | PARTITION_NAME | SUBPARTITION_NAME | PARTITION_ORDINAL_POSITION | SUBPARTITION_ORDINAL_POSITION | PARTITION_METHOD | SUBPARTITION_METHOD | PARTITION_EXPRESSION | SUBPARTITION_EXPRESSION | PARTITION_DESCRIPTION | TABLE_ROWS | AVG_ROW_LENGTH | DATA_LENGTH | MAX_DATA_LENGTH | INDEX_LENGTH | DATA_FREE | CREATE_TIME         | UPDATE_TIME         | CHECK_TIME | CHECKSUM | PARTITION_COMMENT | NODEGROUP | TABLESPACE_NAME |
  4. +---------------+--------------------+------------------------------------------------------+----------------+-------------------+----------------------------+-------------------------------+------------------+---------------------+----------------------+-------------------------+-----------------------+------------+----------------+-------------+-----------------+--------------+-----------+---------------------+---------------------+------------+----------+-------------------+-----------+-----------------+
  5. | def           | ddm_console        | ddm_group                                            | NULL           | NULL              |                       NULL |                          NULL | NULL             | NULL                | NULL                 | NULL                    | NULL                  |          4 |           4096 |       16384 |               0 |            0 |         0 | 2021-09-30 14:02:51 | 2021-09-30 15:38:14 | NULL       |     NULL |                   |           | NULL            |
  6. | def           | ddm_console        | ddm_group_config_file                                | NULL           | NULL              |                       NULL |                          NULL | NULL             | NULL                | NULL                 | NULL                    | NULL                  |          0 |              0 |       16384 |               0 |        32768 |         0 | 2021-09-30 14:02:52 | NULL                | NULL       |     NULL |                   |           | NULL            |
  7. | def           | ddm_console        | ddm_host_info                                        | NULL           | NULL              |                       NULL |                          NULL | NULL             | NULL                | NULL                 | NULL                    | NULL                  |          1 |          16384 |       16384 |               0 |            0 |         0 | 2021-09-30 14:02:51 | 2021-09-30 14:23:35 | NULL       |     NULL |                   |           | NULL            |
  8. | def           | ddm_console        | ddm_instance                                         | NULL           | NULL              |                       NULL |                          NULL | NULL             | NULL                | NULL                 | NULL                    | NULL                  |          1 |          16384 |       16384 |               0 |        32768 |         0 | 2021-09-30 14:02:52 | 2021-09-30 14:39:30 | NULL       |     NULL |                   |           | NULL            |
  9. | def           | ddm_console        | ddm_map_file                                         | NULL           | NULL              |                       NULL |                          NULL | NULL             | NULL                | NULL                 | NULL                    | NULL                  |          0 |              0 |       16384 |               0 |        32768 |         0 | 2021-09-30 14:02:53 | NULL                | NULL       |     NULL |                   |           | NULL            |
  10. | def           | information_schema | ADMINISTRABLE_ROLE_AUTHORIZATIONS                    | NULL           | NULL              |                       NULL |                          NULL | NULL             | NULL                | NULL                 | NULL                    | NULL                  |          0 |              0 |           0 |               0 |            0 |         0 | 2021-09-10 09:58:58 | NULL                | NULL       |     NULL |                   |           | NULL            |

PROCESSLIST表示当前由服务器中执行的线程组执行的操作。PROCESSLIST表是流程信息的一个来源。与show processlist语句的输出类似，PROCESSLIST表提供关于所有线程的信息，即使是属于其他用户的线程(如果您拥有PROCESS特权)。

  1. mysql> select * from processlist;
  2. +----+-----------------+-----------------+--------------------+---------+---------+------------------------+---------------------------+
  3. | ID | USER            | HOST            | DB                 | COMMAND | TIME    | STATE                  | INFO                      |
  4. +----+-----------------+-----------------+--------------------+---------+---------+------------------------+---------------------------+
  5. | 27 | root            | localhost:64617 | information_schema | Query   |       0 | executing              | select * from processlist |
  6. | 28 | root            | localhost:62442 | information_schema | Sleep   |      23 |                        | NULL                      |
  7. |  5 | event_scheduler | localhost       | NULL               | Daemon  | 1344848 | Waiting on empty queue | NULL                      |
  8. +----+-----------------+-----------------+--------------------+---------+---------+------------------------+---------------------------+
  9. 3 rows in set (0.29 sec)

PROFILING表提供语句分析信息。它的内容对应于SHOW PROFILE和SHOW PROFILES语句生成的信息。
ROUTINES表提供有关存储例程(存储过程和存储函数)的信息。
SCHEMATA表提供了当前mysql实例中所有数据库的信息。show databases的结果取之此表。

  1. mysql> select * from schemata;
  2. +--------------+--------------------+----------------------------+------------------------+----------+--------------------+
  3. | CATALOG_NAME | SCHEMA_NAME        | DEFAULT_CHARACTER_SET_NAME | DEFAULT_COLLATION_NAME | SQL_PATH | DEFAULT_ENCRYPTION |
  4. +--------------+--------------------+----------------------------+------------------------+----------+--------------------+
  5. | def          | mysql              | utf8mb4                    | utf8mb4_0900_ai_ci     |     NULL | NO                 |
  6. | def          | information_schema | utf8                       | utf8_general_ci        |     NULL | NO                 |
  7. | def          | performance_schema | utf8mb4                    | utf8mb4_0900_ai_ci     |     NULL | NO                 |
  8. | def          | sys                | utf8mb4                    | utf8mb4_0900_ai_ci     |     NULL | NO                 |
  9. | def          | ddm_console        | utf8mb4                    | utf8mb4_0900_ai_ci     |     NULL | NO                 |
  10. +--------------+--------------------+----------------------------+------------------------+----------+--------------------+
  11. 5 rows in set (0.00 sec)

SCHEMA_PRIVILEGES表提供关于数据库的权限信息。它从mysql.db系统表中获取其值。

  1. mysql> select * from schema_privileges;
  2. +-----------------------------+---------------+--------------------+----------------+--------------+
  3. | GRANTEE                     | TABLE_CATALOG | TABLE_SCHEMA       | PRIVILEGE_TYPE | IS_GRANTABLE |
  4. +-----------------------------+---------------+--------------------+----------------+--------------+
  5. | 'mysql.sys'@'localhost'     | def           | sys                | TRIGGER        | NO           |
  6. | 'mysql.session'@'localhost' | def           | performance_schema | SELECT         | NO           |
  7. +-----------------------------+---------------+--------------------+----------------+--------------+
  8. 2 rows in set (0.00 sec)

STATISTICS表提供了关于表索引的信息。show index from schemaname.tablename的结果取之此表。
TABLES表：提供了关于数据库中的表的信息（包括视图）。详细表述了某个表属于哪个schema，表类型，表引擎，创建时间等信息。show tables from schemaname的结果取之此表。

  1. mysql> select * from tables;
  2. +---------------+--------------------+------------------------------------------------------+-------------+--------------------+---------+------------+------------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+--------------------+----------+---------------------------------------+------------------------------------------+
  3. | 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                            |
  4. +---------------+--------------------+------------------------------------------------------+-------------+--------------------+---------+------------+------------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+--------------------+----------+---------------------------------------+------------------------------------------+
  5. | def           | mysql              | columns_priv                                         | BASE TABLE  | InnoDB             |      10 | Dynamic    |          0 |              0 |       16384 |               0 |            0 |   4194304 |           NULL | 2021-09-10 09:58:46 | NULL                | NULL       | utf8_bin           |     NULL | row_format=DYNAMIC stats_persistent=0 | Column privileges                        |
  6. | def           | mysql              | component                                            | BASE TABLE  | InnoDB             |      10 | Dynamic    |          0 |              0 |       16384 |               0 |            0 |   4194304 |              1 | 2021-09-10 09:58:46 | NULL                | NULL       | utf8_general_ci    |     NULL | row_format=DYNAMIC                    | Components                               |
  7. | def           | mysql              | db                                                   | BASE TABLE  | InnoDB             |      10 | Dynamic    |          2 |           8192 |       16384 |               0 |        16384 |   4194304 |           NULL | 2021-09-10 09:58:46 | NULL                | NULL       | utf8_bin           |     NULL | row_format=DYNAMIC stats_persistent=0 | Database privileges                      |
  8. | def           | mysql              | default_roles                                        | BASE TABLE  | InnoDB             |      10 | Dynamic    |          0 |              0 |       16384 |               0 |            0 |   4194304 |           NULL | 2021-09-10 09:58:46 | NULL                | NULL       | utf8_bin           |     NULL | row_format=DYNAMIC stats_persistent=0 | Default roles                            |
  9. ...
  10. | def           | sys                | x$waits_by_user_by_latency                           | VIEW        | NULL               |    NULL | NULL       |       NULL |           NULL |        NULL |            NULL |         NULL |      NULL |           NULL | 2021-09-10 09:58:56 | NULL                | NULL       | NULL               |     NULL | NULL                                  | VIEW                                     |
  11. | def           | sys                | x$waits_global_by_latency                            | VIEW        | NULL               |    NULL | NULL       |       NULL |           NULL |        NULL |            NULL |         NULL |      NULL |           NULL | 2021-09-10 09:58:57 | NULL                | NULL       | NULL               |     NULL | NULL                                  | VIEW                                     |
  12. | def           | ddm_console        | ddm_group                                            | BASE TABLE  | InnoDB             |      10 | Dynamic    |          4 |           4096 |       16384 |               0 |            0 |         0 |           NULL | 2021-09-30 14:02:51 | 2021-09-30 15:38:14 | NULL       | utf8mb4_bin        |     NULL |                                       |                                          |
  13. | def           | ddm_console        | ddm_group_config_file                                | BASE TABLE  | InnoDB             |      10 | Dynamic    |          0 |              0 |       16384 |               0 |        32768 |         0 |              1 | 2021-09-30 14:02:52 | NULL                | NULL       | utf8mb4_bin        |     NULL |                                       |                                          |
  14. | def           | ddm_console        | ddm_host_info                                        | BASE TABLE  | InnoDB             |      10 | Dynamic    |          1 |          16384 |       16384 |               0 |            0 |         0 |           NULL | 2021-09-30 14:02:51 | 2021-09-30 14:23:35 | NULL       | utf8mb4_0900_ai_ci |     NULL |                                       |                                          |
  15. | def           | ddm_console        | ddm_instance                                         | BASE TABLE  | InnoDB             |      10 | Dynamic    |          1 |          16384 |       16384 |               0 |        32768 |         0 |           NULL | 2021-09-30 14:02:52 | 2021-09-30 14:39:30 | NULL       | utf8mb4_bin        |     NULL |                                       |                                          |
  16. | def           | ddm_console        | ddm_map_file                                         | BASE TABLE  | InnoDB             |      10 | Dynamic    |          0 |              0 |       16384 |               0 |        32768 |         0 |              1 | 2021-09-30 14:02:53 | NULL                | NULL       | utf8mb4_bin        |     NULL |                                       |                                          |
  17. +---------------+--------------------+------------------------------------------------------+-------------+--------------------+---------+------------+------------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+--------------------+----------+---------------------------------------+------------------------------------------+
  18. 332 rows in set (0.05 sec)

TRIGGERS表提供了有关触发器的信息。
VIEWS表提供了关于数据库中视图的信息。必须具有SHOW VIEW权限才能访问该表。

  1. INFORMATION_SCHEMA InnoDB Tables InnoDB表

InnoDB表具体信息可以查看官网介绍：https://dev.mysql.com/doc/refman/8.0/en/innodb-information-schema-tables.html，下面对一些表的内容做简要介绍：
INNODB_BUFFER_PAGE表提供了InnoDB缓冲池中每个页面的信息。
INNODB_BUFFER_POOL_STATS表提供了InnoDB缓冲池状态信息，包括缓冲池容量、空闲页数、已修改(脏的)数据库页的数量等等，show engine innodb status的结果取之此表。
INNODB_COLUMNS表提供了InnoDB表列的元数据，包括列名、列的长度、列的主要类型和精确类型等信息。

  1. mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_COLUMNS where TABLE_ID = 1062\G
  2. *************************** 1. row ***************************
  3.      TABLE_ID: 1062
  4.          NAME: variable
  5.           POS: 0
  6.         MTYPE: 12
  7.        PRTYPE: 16716047
  8.           LEN: 512
  9.   HAS_DEFAULT: 0
  10. DEFAULT_VALUE: NULL
  11. *************************** 2. row ***************************
  12.      TABLE_ID: 1062
  13.          NAME: value
  14.           POS: 1
  15.         MTYPE: 12
  16.        PRTYPE: 16715791
  17.           LEN: 512
  18.   HAS_DEFAULT: 0
  19. DEFAULT_VALUE: NULL
  20. *************************** 3. row ***************************
  21.      TABLE_ID: 1062
  22.          NAME: set_time
  23.           POS: 2
  24.         MTYPE: 3
  25.        PRTYPE: 525319
  26.           LEN: 4
  27.   HAS_DEFAULT: 0
  28. DEFAULT_VALUE: NULL
  29. *************************** 4. row ***************************
  30.      TABLE_ID: 1062
  31.          NAME: set_by
  32.           POS: 3
  33.         MTYPE: 12
  34.        PRTYPE: 16715791
  35.           LEN: 512
  36.   HAS_DEFAULT: 0
  37. DEFAULT_VALUE: NULL
  38. 4 rows in set (0.00 sec)

INNODB_DATAFILES表提供了InnoDB file-per-table和一般表空间的数据文件路径信息。

  1. mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_DATAFILES WHERE SPACE = 8\G
  2. *************************** 1. row ***************************
  3. SPACE: 0x38
  4.  PATH: .\ddm_console\ddm_group.ibd
  5. 1 row in set (0.00 sec)

INNODB_FIELDS表提供了关于InnoDB索引的关键列(字段)的元数据。

  1. mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_FIELDS WHERE INDEX_ID = 165\G
  2. *************************** 1. row ***************************
  3. INDEX_ID: 0x313635
  4.     NAME: ddm_group_id
  5.      POS: 0
  6. 1 row in set (0.00 sec)

INNODB_FOREIGN表提供了关于InnoDB外键的元数据。

  1. mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_FOREIGN\G
  2. *************************** 1. row ***************************
  3.       ID: ddm_console/fk_ddm_instance_ddm_group1
  4. FOR_NAME: ddm_console/ddm_instance
  5. REF_NAME: ddm_console/ddm_group
  6.   N_COLS: 1
  7.     TYPE: 48
  8. *************************** 2. row ***************************
  9.       ID: ddm_console/fk_ddm_instance_ddm_host_info1
  10. FOR_NAME: ddm_console/ddm_instance
  11. REF_NAME: ddm_console/ddm_host_info
  12.   N_COLS: 1
  13.     TYPE: 48
  14. *************************** 3. row ***************************
  15.       ID: ddm_console/fk_group_config_file_ddm_group1
  16. FOR_NAME: ddm_console/ddm_group_config_file
  17. REF_NAME: ddm_console/ddm_group
  18.   N_COLS: 1
  19.     TYPE: 48
  20. *************************** 4. row ***************************
  21.       ID: ddm_console/fk_map_file_ddm_group1
  22. FOR_NAME: ddm_console/ddm_map_file
  23. REF_NAME: ddm_console/ddm_group
  24.   N_COLS: 1
  25.     TYPE: 48
  26. 4 rows in set (0.02 sec)

INNODB_INDEXES表提供了InnoDB索引的元数据。包括索引名，类型，所属表ID和在B-tree的根叶号等等。

  1. mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_INDEXES WHERE TABLE_ID = 1070\G
  2. *************************** 1. row ***************************
  3.        INDEX_ID: 166
  4.            NAME: PRIMARY
  5.        TABLE_ID: 1070
  6.            TYPE: 3
  7.        N_FIELDS: 15
  8.         PAGE_NO: 4
  9.           SPACE: 9
  10. MERGE_THRESHOLD: 50
  11. *************************** 2. row ***************************
  12.        INDEX_ID: 167
  13.            NAME: fk_ddm_instance_ddm_group1_idx
  14.        TABLE_ID: 1070
  15.            TYPE: 0
  16.        N_FIELDS: 2
  17.         PAGE_NO: 5
  18.           SPACE: 9
  19. MERGE_THRESHOLD: 50
  20. *************************** 3. row ***************************
  21.        INDEX_ID: 168
  22.            NAME: fk_ddm_instance_ddm_host_info1_idx
  23.        TABLE_ID: 1070
  24.            TYPE: 0
  25.        N_FIELDS: 2
  26.         PAGE_NO: 6
  27.           SPACE: 9
  28. MERGE_THRESHOLD: 50
  29. 3 rows in set (0.00 sec)
  1. INFORMATION_SCHEMA Thread Pool Tables 线程池表

线程池表具体信息可以查看官网介绍：https://dev.mysql.com/doc/refman/8.0/en/thread-pool-information-schema-tables.html，下面对一些表的内容做简要介绍：
TP_THREAD_GROUP_STATE提供了线程池线程组状态信息
TP_THREAD_GROUP_STATS提供了线程组统计信息
TP_THREAD_STATE提供了线程池线程状态的信息

  1. INFORMATION_SCHEMA Connection-Control Tables 连接控制表

  2. INFORMATION_SCHEMA MySQL Enterprise Firewall Tables 企业防火墙表