如何通过正确索引来提高此查询性能？

Question

您好，我有一个查询，我需要提高此查询的性能。任何人都建议我如何将聚集索引扫描转换为索引搜索。

DECLARE @now DateTime;      
DECLARE @lastweekstart DateTime;      
DECLARE @lastweekend DateTime;      


SET @now = getDate();      
SET @lastweekstart = DATEADD(      
                 DD,      
                 -(DATEPART(DW, @now - 14) - 1),      
                 @now - 14);       
SET @lastweekend = DATEADD(      
               DD,      
               7 - (DATEPART(DW, @now - 14)),      
               @now - 14);      



SELECT Distinct CHINFO.CHILDID,
        COUNT(*)  as PREVIOUSWEEKSACCIDENTS       
FROM  BKA.CHILDINFORMATION CHINFO       
JOIN  BKA.CHILDEVENTS CHE       
       ON CHE.CHILDID = CHINFO.CHILDID        
JOIN BKA.CHILDEVENTPROPERITIES CHEP       
        ON  CHE.EVENTID = CHEP.EVENTID           
WHERE (CHE.TYPE = 'ACCIDENT' OR (CHE.TYPE = 'POTTYBREAK' AND CHEP.PROPERTY = 'SUCCESS'       
        AND CHEP.PROPERTYVALUE = 'FALSE'))           
        AND CHE.ADDDATE BETWEEN @lastweekstart AND @lastweekend       
        GROUP BY CHINFO.CHILDID

任何建议????????????

编辑：

主键：

TableName - ＆gt;的ColumnName

CHILDINFORMATION - ＆GT; childID的

CHILDEVENTS - ＆GT; EVENTID

CHILDEVENTPROPERITIES - ＆GT; EventPropertyId

外键：

CHILDEVENTPROPERITIES - ＆gt;这里EventId是CHILDEVENTS表的外键引用

CHILDEVENTS - ＆gt;这里ChildId是CHILDINFORMATION表的外键引用

NonClustered Indexes：

CHILDINFORMATION - ＆gt;没有非聚集索引

ChildEventProperities - ＆GT; IX_CHILDEVENTproperities_EventId - ＆GT;事件ID

ChildEvents - ＆GT; IX_ChildEvents_Type - ＆GT;类型

ChildEvents - ＆GT; IX_ChildEvents_Type_AddDate - ＆GT;类型，ADDDATE

Answer 1

尝试将您的JOIN替换为LEFT JOIN？如果您使用GROUP BY

，请删除DISTINCT

SELECT CHINFO.CHILDID,
        COUNT(*) AS PREVIOUSWEEKSACCIDENTS       
FROM  BKA.CHILDINFORMATION CHINFO       
LEFT JOIN  BKA.CHILDEVENTS CHE       
       ON CHE.CHILDID = CHINFO.CHILDID        
LEFT JOIN BKA.CHILDEVENTPROPERITIES CHEP       
        ON  CHE.EVENTID = CHEP.EVENTID           
WHERE (CHE.TYPE = 'ACCIDENT' OR (CHE.TYPE = 'POTTYBREAK' AND CHEP.PROPERTY = 'SUCCESS'       
        AND CHEP.PROPERTYVALUE = 'FALSE'))           
        AND CHE.ADDDATE BETWEEN @lastweekstart AND @lastweekend       
        GROUP BY CHINFO.CHILDID

Answer 2

在CHILDEVENTS.ADDDATE上创建单列非聚簇索引。您当前的综合指数可能被＆＃34;或＆＃34;或者对这两种TYPE缺乏选择性。如果将TYPE添加为索引的第二列，则可能会得到一些改进。

现在，如果您刚刚启动此系统并且在CHILDEVENTS表中没有任何重要数据，那么它将会扫描。