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我有一个 CTE 查询似乎会导致大量逻辑读取(或者它可能不会)。我已经运行了 SQL Server Profiler 跟踪,并且此查询似乎一直是运行时间最长的查询之一。(每次点击页面都会调用它)

基本上我想知道我的 CTE 是否正确优化,或者可以改进。

SET STATISTICS IO ON;
GO
    ;WITH cte (PageId, PageTitle, PageType, PageHeadingId, ParentPage, InNavigation, OrgLevel, SortKey, PageOrder, PathLength, PathName, Active) AS
     (
      SELECT
        PageId, 
        PageTitle,
        PageType,
        PageHeadingId,
        ParentPage, 
        InNavigation,
        0, 
        CAST (PageOrder  AS VARBINARY(200)), 
        PageOrder, 
        0 AS PathLength, 
        CAST('' as varchar(300)) AS PathName,
        Active
       FROM dbo.ContentPage
       WHERE ParentPage = 0
        AND InNavigation = 1
      UNION ALL
      SELECT
        b.PageId, 
        b.PageTitle, 
        b.PageType,
        b.PageHeadingId,
        b.ParentPage,
        b.InNavigation, 
        cte.OrgLevel+1,
        CAST(cte.SortKey + CAST (b.PageOrder AS BINARY(4)) AS VARBINARY(200)),
        b.PageOrder, 
        ((cte.OrgLevel+1) + len('....'+b.PageTitle)) as PathLength,
        CAST ((cte.PathName+'....') AS VARCHAR(300)) AS PathName,
        b.Active
       FROM dbo.ContentPage b
         JOIN cte ON b.ParentPage = cte.PageId
       WHERE b.PageType NOT IN (4, 8, 11, 12, 14)
        -- Remove specific page types from the ContentPage table
     )
    SELECT *, (PathName+PageTitle) AS Hierarchy 
    FROM cte WHERE InNavigation = 1     
    ORDER BY SortKey--, PageOrder
SET STATISTICS IO OFF;
GO

如果我离开这条线:

WHERE b.PageType NOT IN (4, 8, 11, 12, 14)

出,然后逻辑读取的数量从〜8500跳到〜13000

(查询所做的是在 ASP.NET 中构建下拉菜单层次结构)如果逻辑读取没问题,那么我假设我必须想出另一种方法来缓存/存储这个菜单(更新 2 或一周3次)

谢谢

ContentPage 的表结构

CREATE TABLE [dbo].[ContentPage](
    [PageId] [int] IDENTITY(1,1) NOT NULL,
    [PageTitle] [nvarchar](150) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
    [PageQuote] [nvarchar](400) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
    [MetaKeywords] [nvarchar](200) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
    [MetaDescription] [ntext] COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
    [PageContent] [ntext] COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
    [Active] [bit] NOT NULL CONSTRAINT [DF_ContentPage_Active]  DEFAULT ((0)),
    [InNavigation] [bit] NOT NULL CONSTRAINT [DF_ContentPage_InNavigation]  DEFAULT ((1)),
    [PageOrder] [int] NOT NULL CONSTRAINT [DF_ContentPage_PageOrder]  DEFAULT ((50)),
    [ParentPage] [int] NOT NULL CONSTRAINT [DF_ContentPage_ParentPage]  DEFAULT ((0)),
    [PageType] [int] NOT NULL CONSTRAINT [DF_ContentPage_PageType]  DEFAULT ((1)),
    [CreatedBy] [nvarchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
    [CreatedOn] [datetime] NULL,
    [ModifiedBy] [nvarchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
    [ModifiedOn] [datetime] NULL,
    [PageViews] [int] NOT NULL CONSTRAINT [DF_ContentPage_PageViews]  DEFAULT ((0)),
    [Emailed] [int] NOT NULL CONSTRAINT [DF_ContentPage_Emailed]  DEFAULT ((0)),
    [Emailable] [bit] NOT NULL CONSTRAINT [DF_ContentPage_Emailable]  DEFAULT ((1)),
    [Printable] [bit] NOT NULL CONSTRAINT [DF_ContentPage_Printable]  DEFAULT ((1)),
    [ContactButton] [bit] NOT NULL CONSTRAINT [DF_ContentPage_PDFable]  DEFAULT ((0)),
    [PageHeadingId] [int] NULL CONSTRAINT [DF_ContentPage_PadeHeadingId]  DEFAULT ((0)),
    [AlternativeTitle] [nvarchar](150) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
    [RighthandImage] [nvarchar](250) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
    [IsMicrosite] [bit] NOT NULL CONSTRAINT [DF_ContentPage_IsMicrosite]  DEFAULT ((0)),
 CONSTRAINT [PK_ContentPage] PRIMARY KEY CLUSTERED 
(
    [PageId] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
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1 回答 1

0

您的 CTE 使用内部 JOIN 回到自身 - 所以这里有一种外键关系:

FROM dbo.ContentPage b
JOIN cte ON b.ParentPage = cte.PageId

因此,打开一个索引b.ParentPage并打开另一个索引PageId可能会有所帮助。

此外,您的查询在and上有WHERE子句,因此您应该考虑在(或可能组合)上的索引。b.PageTypeInNavigationPageType(PageType, InNavigation)

此外,您正在根据SortKey哪个进行排序,PageOrder因此索引可能也很有用。

尝试一次创建一个索引,重新运行您的查询,比较您的统计数据和数字 - 然后确定哪些对您真正有益(哪些没有)。索引不是一门精确的科学——你不能总是预测什么有帮助和有效,什么没有——你必须尝试它并与你的原始查询进行比较,然后决定什么有帮助,什么没有。

于 2011-12-12T12:07:17.830 回答