这有点棘手，但可以使用嵌套的窗口聚合函数（如

SELECT timestamp, UserID, URL,
   SUM(newSession) -- cumulative sum over 0/1
   OVER (PARTITION BY UserId
         ORDER BY timestamp
         ROWS UNBOUNDED PRECEDING) AS SessionID
FROM
 (
   SELECT 
      ts_col, UserID, URL,
      -- calculate the timestamp difference between current and previous row
      CASE WHEN timestamp - LAG(timestamp) 
                            OVER (PARTITION BY UserId 
                                  ORDER BY timestamp) > INTERVAL 'X minutes' 
           THEN 1  -- new session starts
           ELSE 0  -- part of the old session
      END AS newSession
 ) AS dt

一些dbmse（例如vertica和aster）支持使用内置函数进行会话，而在其他dbmse中，您可以实现用户定义的函数。