如何提高LINQ查詢的性能

Question

我有一個查詢從一個視圖調用TheSQLView - 並加入一個表TheSQLTable - 從該視圖獲取結果列表。 如果我從視圖中獲取每條記錄，那么將有大約2000個結果。 僅執行此操作大約需要40秒。 即使我使用where子句返回40個結果，它仍然需要大約8秒。

這是一些代碼：

using (var db = new SQLEntities(_connStr))
{
   var query = from x in db.TheSQLView
               join y in db.TheSQLTable on x.ID equals y.ID
               select new BSTProject()
               {
                  ID = x.ID,
                  Name = x.Name,
                  ... snipped for brevity (about 12 more properties) ...
                  // The two joined properties
                  PctCompleted = y.PctCompleted == null ? 0 : y.PctCompleted,
                  IsCompleted = y.IsCompleted
               };

   return query.toList();
}

我假設它可能與加入桌面視圖有關？

編輯1：運行 SQL事件探查器，此查詢正在執行的內容：

SELECT 
[Project1].[IsCompleted] AS [IsCompleted], 
[Project1].[ID] AS [ID], 
[Project1].[Name] AS [Name], 
[Project1].[org_code] AS [org_code], 
[Project1].[GroupName] AS [GroupName], 
[Project1].[clnt_name] AS [clnt_name], 
[Project1].[start_date] AS [start_date], 
[Project1].[PRIcode] AS [PRIcode], 
[Project1].[PRI] AS [PRI], 
[Project1].[PMcode] AS [PMcode], 
[Project1].[PM] AS [PM], 
[Project1].[DPMcode] AS [DPMcode], 
[Project1].[DPM] AS [DPM], 
[Project1].[ADMcode] AS [ADMcode], 
[Project1].[ADM] AS [ADM], 
[Project1].[PhaseBudgetsTotal] AS [PhaseBudgetsTotal], 
[Project1].[PhasesEffortTotal] AS [PhasesEffortTotal], 
[Project1].[PhasesBudgetRemaining] AS [PhasesBudgetRemaining], 
[Project1].[PhasesOver] AS [PhasesOver], 
[Project1].[C1] AS [C1]
FROM ( SELECT 
    [Extent1].[org_code] AS [org_code], 
    [Extent1].[GroupName] AS [GroupName], 
    [Extent1].[ID] AS [ID], 
    [Extent1].[Name] AS [Name], 
    [Extent1].[clnt_name] AS [clnt_name], 
    [Extent1].[start_date] AS [start_date], 
    [Extent1].[PRIcode] AS [PRIcode], 
    [Extent1].[PRI] AS [PRI], 
    [Extent1].[PMcode] AS [PMcode], 
    [Extent1].[PM] AS [PM], 
    [Extent1].[DPMcode] AS [DPMcode], 
    [Extent1].[DPM] AS [DPM], 
    [Extent1].[ADMcode] AS [ADMcode], 
    [Extent1].[ADM] AS [ADM], 
    [Extent1].[PhaseBudgetsTotal] AS [PhaseBudgetsTotal], 
    [Extent1].[PhasesEffortTotal] AS [PhasesEffortTotal], 
    [Extent1].[PhasesBudgetRemaining] AS [PhasesBudgetRemaining], 
    [Extent1].[PhasesOver] AS [PhasesOver], 
    [Extent2].[IsCompleted] AS [IsCompleted], 
    CASE WHEN ([Extent2].[PctCompleted] IS NULL) THEN cast(0 as decimal(18)) ELSE [Extent2].[PctCompleted] END AS [C1]
    FROM  (SELECT 
[TheSQLView].[org_code] AS [org_code], 
[TheSQLView].[GroupName] AS [GroupName], 
[TheSQLView].[ID] AS [ID], 
[TheSQLView].[Name] AS [Name], 
[TheSQLView].[clnt_name] AS [clnt_name], 
[TheSQLView].[start_date] AS [start_date], 
[TheSQLView].[PRIcode] AS [PRIcode], 
[TheSQLView].[PRI] AS [PRI], 
[TheSQLView].[PMcode] AS [PMcode], 
[TheSQLView].[PM] AS [PM], 
[TheSQLView].[DPMcode] AS [DPMcode], 
[TheSQLView].[DPM] AS [DPM], 
[TheSQLView].[ADMcode] AS [ADMcode], 
[TheSQLView].[ADM] AS [ADM], 
[TheSQLView].[PhaseBudgetsTotal] AS [PhaseBudgetsTotal], 
[TheSQLView].[PhasesEffortTotal] AS [PhasesEffortTotal], 
[TheSQLView].[PhasesBudgetRemaining] AS [PhasesBudgetRemaining], 
[TheSQLView].[PhasesOver] AS [PhasesOver]
FROM [dbo].[TheSQLView] AS [TheSQLView]) AS [Extent1]
    INNER JOIN (SELECT 
[TheSQLTable].[ID] AS [ID], 
[TheSQLTable].[IsCompleted] AS [IsCompleted], 
[TheSQLTable].[PctCompleted] AS [PctCompleted]
FROM [dbo].[TheSQLTable] AS [TheSQLTable]) AS [Extent2] ON [Extent1].[ID] = [Extent2].[ID]
)  AS [Project1]
ORDER BY [Project1].[ID] ASC

Answer 1

你的問題中有很少的信息。 生成的SQL很不錯，但如果您還從SQL事件探查器發布了cpu +邏輯讀取計數器，那就更好了。

但是，我會回答一下：查看索引視圖（聚集索引不少）。 我強烈懷疑你的觀點沒有。 在這里找一些鏈接讓你前往： https ： //stackoverflow.com/a/3986540/1736944

一個警告：如果您沒有使用SQL Server企業版，那么您的查詢必須包含“WITH（NOEXPAND）”提示。 只需創建第二個視圖，從第一個視圖中選擇所有行，並在EF查詢中引用第二個視圖。 使用SQL事件探查器+查詢計划確認您獲得了合理的查詢計划。