0
我希望能够创建一个函数,它接受一个“标准化”查询集,该查询集具有整数id字段和时间戳作为列,然后修改查询集按每个30分钟块中的数量进行计数。下面的代码适用于30分钟的块,如果你用真正的查询替换Q并执行WITH(QUERY)Q.但是我希望能够传入任何适合该类型的查询,然后返回新的SETOF range_durations_type。Postgres函数,需要一个时间间隔并返回一个结果集
CREATE TYPE range_durations_type AS (dtime TIMESTAMP, counts BIGINT);
CREATE TYPE object_datetime AS (id INTEGER, dtime TIMESTAMP);
CREATE OR REPLACE FUNCTION time_range_durations(Q range_durations_type, start_date TIMESTAMP, end_date TIMESTAMP)
RETURNS SETOF range_durations_type AS $$
BEGIN
RETURN QUERY WITH q_cleaned AS (
SELECT
Q.id,
Q.dtime,
Q.dtime - (
(extract(EPOCH FROM Q.dtime :: TIMESTAMP)) :: INTEGER -
extract(EPOCH FROM Q.dtime :: TIMESTAMP) :: INTEGER/1800 * 1800
) * INTERVAL '1 second' AS rounded_dtime
FROM Q
)
SELECT
series.dtime,
count(q_cleaned.id)
FROM (
SELECT
*
FROM
generate_series(start_date, end_date, '30 minutes') dtime) series
LEFT JOIN q_cleaned ON series.dtime = q_cleaned.rounded_dtime
GROUP BY 1
ORDER BY 1;
END;
$$ LANGUAGE plpgsql;
OT,但是......你知道Postgres有范围类型,对吗? http://www.postgresql.org/docs/current/static/rangetypes.html –
是的,我一直在经历的类型,看看他们中的任何一个会工作。我对他们不够熟悉......感谢提示。 – hazmat