sql - 使用窗口函数计算每个事件行在给定间隔内事件的先前发生次数

Question

我有表存储用户发生的事件，如 http://sqlfiddle.com/#!15/2b559/2/0 所示。

event_id(integer)
user_id(integer)
event_type(integer)
timestamp(timestamp)

数据样本如下所示:

+-----------+----------+-------------+----------------------------+
| event_id  | user_id  | event_type  |         timestamp          |
+-----------+----------+-------------+----------------------------+
|        1  |       1  |          1  | January, 01 2015 00:00:00  |
|        2  |       1  |          1  | January, 10 2015 00:00:00  |
|        3  |       1  |          1  | January, 20 2015 00:00:00  |
|        4  |       1  |          1  | January, 30 2015 00:00:00  |
|        5  |       1  |          1  | February, 10 2015 00:00:00 |
|        6  |       1  |          1  | February, 21 2015 00:00:00 |
|        7  |       1  |          1  | February, 22 2015 00:00:00 |
+-----------+----------+-------------+----------------------------+

对于每个事件，我想获取事件发生前 30 天内发生的同一用户和同一事件类型的事件数。

它应该如下所示:

+-----------+----------+-------------+-----------------------------+-------+
| event_id  | user_id  | event_type  |         timestamp           | count |
+-----------+----------+-------------+-----------------------------+-------+
|        1  |       1  |          1  | January, 01 2015 00:00:00   |     1 |
|        2  |       1  |          1  | January, 10 2015 00:00:00   |     2 |
|        3  |       1  |          1  | January, 20 2015 00:00:00   |     3 |
|        4  |       1  |          1  | January, 30 2015 00:00:00   |     4 |
|        5  |       1  |          1  | February, 10 2015 00:00:00  |     3 |
|        6  |       1  |          1  | February, 21 2015 00:00:00  |     3 |
|        7  |       1  |          1  | February, 22 2015 00:00:00  |     4 |
+-----------+----------+-------------+-----------------------------+-------+

该表包含数百万行，因此我无法按照@jpw 在下面的答案中所建议的那样使用相关子查询。

到目前为止，我通过使用以下查询设法获得了之前发生的具有相同 user_id 和相同 event_id 的事件总数:

SELECT event_id, user_id,event_type,"timestamp",
COUNT(event_type) OVER w
FROM events
WINDOW w AS (PARTITION BY user_id,event_type ORDER BY timestamp
ROWS UNBOUNDED PRECEDING);

结果如下:

+-----------+----------+-------------+-----------------------------+-------+
| event_id  | user_id  | event_type  |         timestamp           | count |
+-----------+----------+-------------+-----------------------------+-------+
|        1  |       1  |          1  | January, 01 2015 00:00:00   |     1 |
|        2  |       1  |          1  | January, 10 2015 00:00:00   |     2 |
|        3  |       1  |          1  | January, 20 2015 00:00:00   |     3 |
|        4  |       1  |          1  | January, 30 2015 00:00:00   |     4 |
|        5  |       1  |          1  | February, 10 2015 00:00:00  |     5 |
|        6  |       1  |          1  | February, 21 2015 00:00:00  |     6 |
|        7  |       1  |          1  | February, 22 2015 00:00:00  |     7 |
+-----------+----------+-------------+-----------------------------+-------+

您知道是否有办法更改窗口框架规范或 COUNT 函数，以便仅返回 x 天内发生的事件数？

第二次，我想排除重复事件，即相同的事件类型和相同的时间戳。

Answer 1

我在 duplicate question on dba.SE 下提供了更详细的答案和 fiddle .

基本上:

CREATE INDEX events_fast_idx ON events (user_id, event_type, ts);

或者:

SELECT *
FROM   events e
    ,  LATERAL (
   SELECT count(*) AS ct
   FROM   events 
   WHERE  user_id    = e.user_id 
   AND    event_type = e.event_type
   AND    ts >= e.ts - interval '30 days'
   AND    ts <= e.ts
   ) ct
ORDER  BY event_id;

或者:

SELECT e.*, count(*) AS ct
FROM   events e
JOIN   events x USING (user_id, event_type)
WHERE  x.ts >= e.ts - interval '30 days'
AND    x.ts <= e.ts
GROUP  BY e.event_id
ORDER  BY e.event_id;