本文介绍查询预降采样规则的语法。

语法

SHOW PREDOWNSAMPLES [ ON table_name ]

参数

参数 必选 描述
table_name 否 时序数据表名。

示例

  • 示例一：返回所有表的预降采样规则。
    SHOW PREDOWNSAMPLES
    返回结果如下：
    +--------+----------+------------+-----+----------------------+
| table  | interval | aggregator | ttl | update_time          |
+--------+----------+------------+-----+----------------------+
| sensor | 1h       | sum, max   | 90d | 2021-10-10T08:00:00Z |
| sensor | 5m       | sum, max   | 30d | 2021-10-10T08:00:00Z |
| test   | 1m       | sum, max   | 30d | 2021-10-10T08:00:00Z |
| test   | 2h       | sum, max   | 30d | 2021-10-10T08:00:00Z |
+--------+----------+------------+-----+----------------------+
  • 示例二：返回sensor表的预降采样规则。
    SHOW PREDOWNSAMPLES ON sensor
    返回结果如下：
    +--------+----------+------------+-----+----------------------+
| table  | interval | aggregator | ttl | update_time          |
+--------+----------+------------+-----+----------------------+
| sensor | 1h       | sum, max   | 90d | 2021-10-10T08:00:00Z |
| sensor | 5m       | sum, max   | 30d | 2021-10-10T08:00:00Z |
+--------+----------+------------+-----+----------------------+