如何在 TimescaleDB 中的一张表上创建多个连续聚合？

Question

我有这个带有超表的series 表。我想对该表中的数据进行不同的连续聚合。

CREATE TABLE series (
    time TIMESTAMPTZ PRIMARY KEY,
    value INTEGER
);

SELECT create_hypertable('series', 'time');

CREATE VIEW mat_view1
WITH (timescaledb.continuous) AS
SELECT time_bucket('1 day', time) AS day,
AVG(value)
FROM series
GROUP BY day;

CREATE VIEW mat_view2
WITH (timescaledb.continuous) AS
SELECT time_bucket('1 week', time) AS week,
COUNT(value)
FROM series
GROUP BY week;

但似乎在 PostgreSQL 11 中是不可能的 - 这是我在运行上面的查询时得到的：

ERROR:  hypertable already has a continuous aggregate
RECOMMENDATION:  hypertables currently only support a single continuous aggregate. Drop the other continuous aggreagate to add a new one.

甚至不可能在同一张表上创建不同的超表。

ERROR:  hypertable already has a continuous aggregate
RECOMMENDATION:  hypertables currently only support a single continuous aggregate. Drop the other continuous aggreagate to add a new one.

是否可以解决此限制？或者我应该使用另一种方法（例如，为每个连续聚合复制series 表：-x）？

Answer 1

从 TimescaleDB 1.4.0 开始支持此功能，请参阅： https://github.com/timescale/timescaledb/blob/master/CHANGELOG.md#140-2019-07-18

以前 Timescale 不支持此功能，但您可以执行以下操作：创建 1 个包含您可能需要的所有详细信息的连续聚合，并为第二个用例创建常规视图。

CREATE VIEW mat_view1
WITH (timescaledb.continuous) AS
SELECT time_bucket('1 day', time) AS day,
AVG(value) AS avg,
COUNT(value) AS count
FROM series
GROUP BY day;

CREATE VIEW view2 AS
SELECT time_bucket('1 week', day) AS week,
SUM(count) AS count
FROM mat_view1
GROUP BY week;