減少排在SQL

Question

我有一個選擇查詢，將返回的東西如下表所示：

 
start | stop | id 
------------------ 
0  | 100 | 1 
1  | 101 | 1 
2  | 102 | 1 
2  | 102 | 2 
5  | 105 | 1 
7  | 107 | 2 
... 
300 | 400 | 1 
370 | 470 | 1 
450 | 550 | 1 

哪裏停止=起動+ N;在這種情況下n = 100。

我想合併重疊每個ID：

 
start | stop | id 
------------------ 
0  | 105 | 1 
2  | 107 | 2 
... 
300 | 550 | 1 

ID 1沒有給出0 - 550，因爲一開始300停止後105

將有幾十萬第一個查詢返回的記錄和n可以達到數萬，所以處理得越快越好。

使用PostgreSQL btw。

Answer 1

WITH bounds AS 
     (
     SELECT *, ROW_NUMBER() OVER (PARTITION BY id ORDER BY start) AS rn 
     FROM (
       SELECT id, LAG(stop) OVER (PARTITION BY id ORDER BY start) AS pstop, start 
       FROM q 
       UNION ALL 
       SELECT id, MAX(stop), NULL 
       FROM q 
       GROUP BY 
         id 
       ) q2 
     WHERE start > pstop OR pstop IS NULL OR start IS NULL 
     ) 
SELECT b2.start, b1.pstop 
FROM bounds b1 
JOIN bounds b2 
ON  b1.id = b2.id 
     AND b1.rn = b2.rn + 1