TABLES

TABLES 表提供数据库中表的信息：

USE INFORMATION_SCHEMA;
DESC TABLES;

结果如下：

+------------------+----------+------+------+---------+---------------+
| Column           | Type     | Key  | Null | Default | Semantic Type |
+------------------+----------+------+------+---------+---------------+
| table_catalog    | String   |      | NO   |         | FIELD         |
| table_schema     | String   |      | NO   |         | FIELD         |
| table_name       | String   |      | NO   |         | FIELD         |
| table_type       | String   |      | NO   |         | FIELD         |
| table_id         | UInt32   |      | YES  |         | FIELD         |
| data_length      | UInt64   |      | YES  |         | FIELD         |
| max_data_length  | UInt64   |      | YES  |         | FIELD         |
| index_length     | UInt64   |      | YES  |         | FIELD         |
| max_index_length | UInt64   |      | YES  |         | FIELD         |
| avg_row_length   | UInt64   |      | YES  |         | FIELD         |
| engine           | String   |      | YES  |         | FIELD         |
| version          | UInt64   |      | YES  |         | FIELD         |
| row_format       | String   |      | YES  |         | FIELD         |
| table_rows       | UInt64   |      | YES  |         | FIELD         |
| data_free        | UInt64   |      | YES  |         | FIELD         |
| auto_increment   | UInt64   |      | YES  |         | FIELD         |
| create_time      | DateTime |      | YES  |         | FIELD         |
| update_time      | DateTime |      | YES  |         | FIELD         |
| check_time       | DateTime |      | YES  |         | FIELD         |
| table_collation  | String   |      | YES  |         | FIELD         |
| checksum         | UInt64   |      | YES  |         | FIELD         |
| create_options   | String   |      | YES  |         | FIELD         |
| table_comment    | String   |      | YES  |         | FIELD         |
| temporary        | String   |      | YES  |         | FIELD         |
+------------------+----------+------+------+---------+---------------+

SELECT * FROM tables WHERE table_schema='public' AND table_name='monitor'\G

*************************** 1. row ***************************
   table_catalog: greptime
    table_schema: public
      table_name: monitor
      table_type: BASE TABLE
        table_id: 1054
     data_length: 0
 max_data_length: 0
    index_length: 0
max_index_length: 0
  avg_row_length: 0
          engine: mito
         version: 11
      row_format: Fixed
      table_rows: 0
       data_free: 0
  auto_increment: 0
     create_time: 2024-07-24 22:06:18.085000
     update_time: NULL
      check_time: NULL
 table_collation: NULL
        checksum: 0
  create_options:
   table_comment: NULL
       temporary: N
1 row in set (0.01 sec)

下方的语句是等价的：

SELECT table_name FROM INFORMATION_SCHEMA.TABLES
  WHERE table_schema = '<db_name>'
  [AND table_name LIKE 'monitor']

SHOW TABLES
  FROM db_name
  [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。