SQL优化/调整

Question

我有这个SQL Server查询

SELECT count(distinct [IP]) as GlobalUniqueIPcount, 
    --RangeUniqueIPcount
    (SELECT count(distinct [IP]) FROM [tblSequence] WHERE SiteID = @siteID AND ([Timestamp] > DATEADD(dd, -@days, (LEFT(GETDATE(),12))))) as RangeUniqueIPcount,
    --RangeUrlUniqueIPcount
    (SELECT count(distinct [IP]) FROM [tblSequence] WHERE SiteID = @siteID AND ([Timestamp] > DATEADD(dd, -@days, (LEFT(GETDATE(),12)))) AND Url = @Url) as RangeUrlUniqueIPcount,
    --RangeUniquePageviews
    (SELECT count (distinct url + SessionGuid) FROM [tblSequence] WHERE SiteID = @siteID AND ([Timestamp] > DATEADD(dd, -@days, (LEFT(GETDATE(),12))))) as RangeUniquePageViews,
    --RangeUrlUniquePageviews
    (SELECT count (distinct url + SessionGuid) FROM [tblSequence] WHERE SiteID = @siteID AND ([Timestamp] > DATEADD(dd, -@days, (LEFT(GETDATE(),12)))) AND Url = @Url) as RangeUrlUniquePageViews,  
    --GlobalUniquePageViews
    (SELECT count (distinct url + SessionGuid) FROM [tblSequence] WHERE SiteID = @siteID) as GlobalUniquePageViews
FROM [tblSequence] WHERE SiteID = @siteID

我有超过1,000,000行，它的表现就像垃圾一样。 怎么做 - 请帮忙。

非常感谢

Answer 1

难怪它运行缓慢：你有5个相关的子查询，其中2个是不必要的，3个可以重写。试试这个。

另外，你需要其中一个索引，不能确切地说明哪个

{li> (SiteID, Timestamp, Url)包含(IP, SessionGuid)的INCLUDE
• (SiteID, Timestamp)在(IP, SessionGuid, Url)
上包含INCLUDE
• (SiteID) with INCLUDE (IP, Url, SessionGuid, Timestamp)

取决于是否使用第一个拖曳RangeMatch和URLmatch。我的猜测是需要2号或3号。这对索引大小很重要。

当未使用*时，Count将忽略NULL。

SELECT
    count(distinct [IP]) as GlobalUniqueIPcount, 

    --RangeUniqueIPcount
    count (distinct CASE
             WHEN RangeMatch = 1 
             THEN IP ELSE NULL
           END ) AS RangeUniqueIPcount,

    --RangeURLUniqueIPcount
    count (distinct CASE
             WHEN RangeMatch = 1  AND UrlMatch = 1
             THEN IP ELSE NULL
           END ) AS RangeURLUniqueIPcount,

    --RangeUniquePageviews
    count (distinct CASE
             WHEN RangeMatch = 1 
             THEN url + SessionGuid ELSE NULL
           END ) RangeUniquePageViews,

    --RangeUrlUniquePageviews
    count (distinct CASE
             WHEN RangeMatch = 1 AND UrlMatch = 1
             THEN url + SessionGuid ELSE NULL
           END ) RangeUrlUniquePageViews,

    --GlobalUniquePageViews
    count (distinct url + SessionGuid) as GlobalUniquePageViews
FROM
  (SELECT
    *, 
    CASE WHEN  Url = @Url THEN 1 ELSE 0 END AS UrlMatch,
    CASE WHEN [Timestamp] > DATEADD(dd, -@days, (LEFT(GETDATE(),12))) THEN 1 ELSE 0 END AS RangeMatch
  FROM
     [tblSequence]
  WHERE SiteID = @siteID
  ) foo

Answer 2

IP SiteID，Timestamp，url和SessionGuid是否已有索引？