同时通话

Question

我正在尝试通过查看日期时间范围来计算特定呼叫时的同时呼叫数。我的查询有效，但只需要约10分钟即可执行95,000条记录，这太长了。任何优化的想法？

SELECT r.*,
       rr.ChannelsActive  'ChannelsActive'
FROM #rg r
OUTER APPLY
(
      SELECT SUM(1) AS ChannelsActive
      FROM #rg r_inner 
      WHERE 
      (
             r_inner.CallStart BETWEEN r.CallStart AND r.CallEnd 
            OR r_inner.CallEnd BETWEEN r.CallStart AND r.CallEnd
            OR r.CallStart BETWEEN r_inner.CallStart AND r_inner.CallEnd 
            OR r.CallEnd BETWEEN r_inner.CallStart AND r_inner.CallEnd

      )
 ) rr

示例数据

CREATE TABLE #rg
  (
     CallStart DATETIME,
     CallEnd   DATETIME
  )

CREATE INDEX ix1
  ON #rg(CallStart, CallEnd)

CREATE INDEX ix2
  ON #rg(CallEnd, CallStart);

WITH T(N, R)
     AS (SELECT TOP (95000) ROW_NUMBER() OVER (ORDER BY (SELECT 0)) AS RN,
                            ABS(120 + 30 * SQRT(-2 * LOG(ABS(CAST(CAST(CRYPT_GEN_RANDOM(8) AS BIGINT) AS FLOAT) / 9223372036854775807))) * COS(2 * PI() * ABS(CAST(CAST(CRYPT_GEN_RANDOM(8) AS BIGINT) AS FLOAT) / 9223372036854775807)))
         FROM   sys.all_objects o1,
                sys.all_objects o2)
INSERT INTO #rg
SELECT DATEADD(SECOND, N, GETDATE()),
       DATEADD(SECOND, N + R, GETDATE())
FROM   T 

Answer 1

这应该这样做：

 ;WITH cteCallEvents As
 (
        SELECT *, CallStart As EventTime, 1 As EventType FROM #rg r
    UNION ALL
        SELECT *, CallEnd   As EventTime, 0 As EventType FROM #rg r
 )
 , cteCallCounts As
 (
    SELECT *,
        ROW_NUMBER() OVER(Order By EventTime) as EventCount,
        ROW_NUMBER() OVER(Partition By EventType Order By EventTime) as TypeCount
    FROM cteCallEvents
 )
 SELECT *,
    2*TypeCount - EventCount  As OpenCalls
FROM    cteCallCounts
WHERE   EventType = 1

最多需要几秒钟。应该适用于任何SQL Server 2005 +。

Answer 2

使用这样的SQL来获取开始/结束事件列表......

Select CallStart, 1 As CallCount From #rg
Union All
Select CallEnd, -1 From #rg
Order By CallStart

...然后将此视为一个简单的运行总计问题，根据您的SQL Server版本进行不同的解决，或者如果可以选择，可以在代码中轻松解决。