TABLES

TABLES 表提供数据库中表的信息：

  1. USE INFORMATION_SCHEMA;
  2. DESC TABLES;

结果如下：

  1. +------------------+----------+------+------+---------+---------------+
  2. | Column           | Type     | Key  | Null | Default | Semantic Type |
  3. +------------------+----------+------+------+---------+---------------+
  4. | table_catalog    | String   |      | NO   |         | FIELD         |
  5. | table_schema     | String   |      | NO   |         | FIELD         |
  6. | table_name       | String   |      | NO   |         | FIELD         |
  7. | table_type       | String   |      | NO   |         | FIELD         |
  8. | table_id         | UInt32   |      | YES  |         | FIELD         |
  9. | data_length      | UInt64   |      | YES  |         | FIELD         |
  10. | max_data_length  | UInt64   |      | YES  |         | FIELD         |
  11. | index_length     | UInt64   |      | YES  |         | FIELD         |
  12. | max_index_length | UInt64   |      | YES  |         | FIELD         |
  13. | avg_row_length   | UInt64   |      | YES  |         | FIELD         |
  14. | engine           | String   |      | YES  |         | FIELD         |
  15. | version          | UInt64   |      | YES  |         | FIELD         |
  16. | row_format       | String   |      | YES  |         | FIELD         |
  17. | table_rows       | UInt64   |      | YES  |         | FIELD         |
  18. | data_free        | UInt64   |      | YES  |         | FIELD         |
  19. | auto_increment   | UInt64   |      | YES  |         | FIELD         |
  20. | create_time      | DateTime |      | YES  |         | FIELD         |
  21. | update_time      | DateTime |      | YES  |         | FIELD         |
  22. | check_time       | DateTime |      | YES  |         | FIELD         |
  23. | table_collation  | String   |      | YES  |         | FIELD         |
  24. | checksum         | UInt64   |      | YES  |         | FIELD         |
  25. | create_options   | String   |      | YES  |         | FIELD         |
  26. | table_comment    | String   |      | YES  |         | FIELD         |
  27. | temporary        | String   |      | YES  |         | FIELD         |
  28. +------------------+----------+------+------+---------+---------------+
  1. SELECT * FROM tables WHERE table_schema='public' AND table_name='monitor'\G
  1. *************************** 1. row ***************************
  2.    table_catalog: greptime
  3.     table_schema: public
  4.       table_name: monitor
  5.       table_type: BASE TABLE
  6.         table_id: 1054
  7.      data_length: 0
  8.  max_data_length: 0
  9.     index_length: 0
  10. max_index_length: 0
  11.   avg_row_length: 0
  12.           engine: mito
  13.          version: 11
  14.       row_format: Fixed
  15.       table_rows: 0
  16.        data_free: 0
  17.   auto_increment: 0
  18.      create_time: 2024-07-24 22:06:18.085000
  19.      update_time: NULL
  20.       check_time: NULL
  21.  table_collation: NULL
  22.         checksum: 0
  23.   create_options:
  24.    table_comment: NULL
  25.        temporary: N
  26. 1 row in set (0.01 sec)

下方的语句是等价的：

  1. SELECT table_name FROM INFORMATION_SCHEMA.TABLES
  2.   WHERE table_schema = '<db_name>'
  3.   [AND table_name LIKE 'monitor']
  5. SHOW TABLES
  6.   FROM db_name
  7.   [LIKE 'monitor']

TABLES 表的字段描述如下：

  • table_catalog：表所属的目录。该值始终为 greptime。
  • table_schema：表所属的数据库。
  • table_name：表的名称。
  • table_type：表的类型。
    • BASE TABLE：基础表
    • TEMPORARY：临时结果集
    • VIEW：视图表
  • table_id：表 ID。
  • engine：该表使用的存储引擎。
  • version: 版本。固定值为 11。
  • create_time: 表创建的时间戳。
  • table_comment: 表的注释。
  • 其他列如 table_rows， row_format 等不支持，仅用于兼容 MySQL。GreptimeDB 未来可能会支持其中的一些列。