同时通话 [英] Simultaneous calls
本文介绍了同时通话的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我正在尝试通过查看日期时间范围来计算在进行特定呼叫时的同时呼叫数.我的查询有效,但是只需要9分钟就能完成95,000条记录,这太长了.有优化的想法吗?
I'm trying to calculate the number of simultaneous calls at the time a particular call is made by looking at the datetime ranges. My query works, but takes ~10 minutes to perform for only 95,000 records, which is too long. Any ideas for optimization?
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
推荐答案
这应该做到:
;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
最多只需要几秒钟.应该可以在任何SQL Server 2005+上使用.
It should take a couple of seconds at most. Should work on any SQL Server 2005+.
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