我有一个像这样的在线会话的表(空行只是为了更好的可见性)：
ip_address | start_time | stop_time ------------|------------------|------------------ 10.10.10.10 | 2016-04-02 08:00 | 2016-04-02 08:12 10.10.10.10 | 2016-04-02 08:11 | 2016-04-02 08:20 10.10.10.10 | 2016-04-02 09:00 | 2016-04-02 09:10 10.10.10.10 | 2016-04-02 09:05 | 2016-04-02 09:08 10.10.10.10 | 2016-04-02 09:05 | 2016-04-02 09:11 10.10.10.10 | 2016-04-02 09:02 | 2016-04-02 09:15 10.10.10.10 | 2016-04-02 09:10 | 2016-04-02 09:12 10.66.44.22 | 2016-04-02 08:05 | 2016-04-02 08:07 10.66.44.22 | 2016-04-02 08:03 | 2016-04-02 08:11
我需要“信封”在线时间跨度：
ip_address | full_start_time | full_stop_time ------------|------------------|------------------ 10.10.10.10 | 2016-04-02 08:00 | 2016-04-02 08:20 10.10.10.10 | 2016-04-02 09:00 | 2016-04-02 09:15 10.66.44.22 | 2016-04-02 08:03 | 2016-04-02 08:11
我有这个查询返回所需的结果：
WITH t AS
-- Determine full time-range of each IP
(SELECT ip_address,MIN(start_time) AS min_start_time,MAX(stop_time) AS max_stop_time FROM IP_SESSIONS GROUP BY ip_address),t2 AS
-- compose ticks
(SELECT DISTINCT ip_address,min_start_time + (LEVEL-1) * INTERVAL '1' MINUTE AS ts
FROM t
CONNECT BY min_start_time + (LEVEL-1) * INTERVAL '1' MINUTE <= max_stop_time),t3 AS
-- get all "online" ticks
(SELECT DISTINCT ip_address,ts
FROM t2
JOIN IP_SESSIONS USING (ip_address)
WHERE ts BETWEEN start_time AND stop_time),t4 AS
(SELECT ip_address,ts,LAG(ts) OVER (PARTITION BY ip_address ORDER BY ts) AS prevIoUs_ts
FROM t3),t5 AS
(SELECT ip_address,SUM(DECODE(prevIoUs_ts,NULL,1,0 + (CASE WHEN prevIoUs_ts + INTERVAL '1' MINUTE <> ts THEN 1 ELSE 0 END)))
OVER (PARTITION BY ip_address ORDER BY ts ROWS UNBOUNDED PRECEDING) session_no
FROM t4)
SELECT ip_address,MIN(ts) AS full_start_time,MAX(ts) AS full_stop_time
FROM t5
GROUP BY ip_address,session_no
ORDER BY 1,2;
但是,我对表现感到担忧.该表有数亿行,时间分辨率为毫秒(不是示例中给出的一分钟).因此,CTE t3将是巨大的.有没有人有避免自我加入和“连接”的解决方案？
单个智能Analytic Function会很棒.
解决方法
试试这个吧.我尽我所能地测试了它,我相信它涵盖了所有的可能性,包括合并相邻的间隔(10:15到10:30和10:30到10:40结合成一个间隔,10：15到10:40 ).它应该也很快,它使用不多.
with m as
(
select ip_address,start_time,max(stop_time) over (partition by ip_address order by start_time
rows between unbounded preceding and 1 preceding) as m_time
from ip_sessions
union all
select ip_address,max(stop_time) from ip_sessions group by ip_address
),n as
(
select ip_address,m_time
from m
where start_time > m_time or start_time is null or m_time is null
),f as
(
select ip_address,lead(m_time) over (partition by ip_address order by start_time) as stop_time
from n
)
select * from f where start_time is not null
/
