SQL Server??????????????????????????
???????????? ???????[ 2013/4/11 10:21:21 ] ????????
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??????2008????????????????????????????1???——??????????filter index??????????????where????????????????????????????????????????????????????????????洢?????????????
?????????????
??????AdventureWorks2012????????Production.WorkOrder??????????????????????
???????裺
????1???????????????????Production.WorkOrder?У?
CREATE INDEX idx_WorkOrder_ScrapReasonID ON Production.WorkOrder(ScrapReasonID)
GO
????2????????????????????????????????????
DBCC SHOW_STATISTICS('Production.WorkOrder'??IX_WorkOrder_ScrapReasonID)
GO
????3????????£?
????4????All denisty?У?????????????????????????????????????
DROP INDEX IX_WorkOrder_ScrapReasonID ON Production.WorkOrderGO CREATE INDEX IX_WorkOrder_ScrapReasonID ON Production.WorkOrder(ScrapReasonID)WHERE ScrapReasonID IS NOT NULL GO
????5???????в???All density?У???????????????
DBCC SHOW_STATISTICS('Production.WorkOrder'??IX_WorkOrder_ScrapReasonID)
GO
DROP INDEX IX_WorkOrder_ScrapReasonID ON Production.WorkOrder
GO
????6????????£?
??????????
?????????????????ж???????????????????????????row sampled????????????????72591?????????729?????????100??????Filter Expression?У??????null??????????
??????All density?У?????????????ScriptReasonID?У?????????????????????????б??????????ScriptReasonID?????????????????????С?
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