實體框架遺漏加入永久（性能問題）

我正在使用實體框架和linq做多個左外連接，但它需要3秒鐘才能通過實體框架運行查詢。實體框架遺漏加入永久（性能問題）

我使用了((System.Data.Objects.ObjectQuery)query).ToTraceString();並在管理工作室測試了sql語句並立即執行。

這裏是linq代碼。

var query = from Inventory in db.INVENTORies       

        join NewInventory in db.NEW_INVENTORY on Inventory.Barcode equals NewInventory.Barcode into lj_1       
        from q_NewInventory in lj_1.DefaultIfEmpty() 
        join Categories in db.Categorys on Inventory.CAT_ID equals Categories.CAT_ID into lj_2 
        from q_Categories in lj_2.DefaultIfEmpty() 
        join SCategories in db.StoneCategories on Inventory.TP_ID equals SCategories.TP_ID into lj_3 
        from q_SubCategory in lj_3.DefaultIfEmpty() 
        join qSupplier in db.Suppliers on Inventory.SUP_ID equals qSupplier.SUP_ID into lj_4 
        from q_Supplier in lj_4.DefaultIfEmpty() 
        join qStatus in db.Statuses on Inventory.ST_ID equals qStatus.ST_ID into lj_5 
        from q_Status in lj_5.DefaultIfEmpty() 
        join q_Locations in db.Locations on Inventory.LOC_ID equals q_Locations.LOC_ID into lj_7 
        from q_locations in lj_7.DefaultIfEmpty() 
        join q_Stone1 in db.Stones on Inventory.StoneID_1 equals q_Stone1.STONE_ID into lj_s1 
        from q_stone1 in lj_s1.DefaultIfEmpty() 
        join q_Stone2 in db.Stones on Inventory.StoneID_2 equals q_Stone2.STONE_ID into lj_s2 
        from q_stone2 in lj_s2.DefaultIfEmpty() 
        join q_Stone3 in db.Stones on Inventory.StoneID_3 equals q_Stone3.STONE_ID into lj_s3 
        from q_stone3 in lj_s3.DefaultIfEmpty() 
        join q_Stone4 in db.Stones on Inventory.StoneID_4 equals q_Stone4.STONE_ID into lj_s4 
        from q_stone4 in lj_s4.DefaultIfEmpty() 
        join q_Stone5 in db.Stones on Inventory.StoneID_5 equals q_Stone5.STONE_ID into lj_s5 
        from q_stone5 in lj_s5.DefaultIfEmpty() 
        join q_Stone6 in db.Stones on Inventory.StoneID_6 equals q_Stone6.STONE_ID into lj_s6 
        from q_stone6 in lj_s6.DefaultIfEmpty() 
        join q_Stone7 in db.Stones on Inventory.StoneID_7 equals q_Stone7.STONE_ID into lj_s7 
        from q_stone7 in lj_s7.DefaultIfEmpty() 
        join q_Stone8 in db.Stones on Inventory.StoneID_8 equals q_Stone8.STONE_ID into lj_s8 
        from q_stone8 in lj_s8.DefaultIfEmpty() 
        join qMasterInventory in db.MASTERINVENTORies on q_NewInventory.InvItemNo equals qMasterInventory.INVITEMNO into lj_6 
        from q_MasterInventory in lj_6.DefaultIfEmpty() 
        where Inventory.Barcode == _Barcode 

        select new 
        { 
         inv_InvID = Inventory.INV_ID, inv_Barcode = Inventory.Barcode, 
         inv_catID = Inventory.CAT_ID, inv_SubCatID = Inventory.TP_ID, inv_Price = Inventory.ITEM_PRICE, inv_Cost = Inventory.ITEM_COST, 
         inv_PricePoint = Inventory.PricePoint, inv_StatusID = Inventory.ST_ID, inv_StID = Inventory.ST_ID, inv_SupID = Inventory.SUP_ID, 
         inv_LocID = Inventory.LOC_ID, inv_LabSupplier = Inventory.LabSupplier, inv_LabStone1 = Inventory.LabStone1, inv_LabCategory = Inventory.LabCategory, 
         inv_LabExtra = Inventory.LabExtra, inv_LabMadeIn = Inventory.LabMadeIn, inv_Width = Inventory.ChainThickNess, inv_Size = Inventory.ChainSize, 
         inv_Stone1 = Inventory.StoneID_1,inv_Stone2 = Inventory.StoneID_2,inv_Stone3 = Inventory.StoneID_3,inv_Stone4 = Inventory.StoneID_4,inv_Stone5 = Inventory.StoneID_5,inv_Stone6 = Inventory.StoneID_6,inv_Stone7 = Inventory.StoneID_7,inv_Stone8 = Inventory.StoneID_8,inv_Stone9 = Inventory.StoneID_9,inv_Stone10 = Inventory.StoneID_10, 
         stat_Status = q_Status.DESCRIPTION, 
         cat_Category = q_Categories.DESCRIPTION, 
         subCat_SubCategory = q_SubCategory.DESCRIPTION, 
         sup_Supplier = q_Supplier.Name, 
         loc_Location = q_locations.DESCRIPTION, 

         mas_SKU = q_MasterInventory.INVITEMNO, 
         mas_GUID = q_MasterInventory.ItemGUID, 

         stone1 = q_stone1.DESCRIPTION, 
         stone2 = q_stone2.DESCRIPTION, 
         stone3 = q_stone3.DESCRIPTION, 
         stone4 = q_stone4.DESCRIPTION, 
         stone5 = q_stone5.DESCRIPTION, 
         stone6 = q_stone6.DESCRIPTION, 
         stone7 = q_stone7.DESCRIPTION, 
         stone8 = q_stone8.DESCRIPTION, 

        };

來源

2012-01-27 Timothy von Hollen

更新統計信息，重建索引... – 2012-01-27 00:59:18

看起來像是模型的問題。石頭1-8？！？ – Phill 2012-01-27 01:20:46

我認爲花在EF上的時間將這個查詢重寫爲SQL。正如Mitch指出的那樣，這個查詢看起來很糟糕，而由它創建的SQL可能會更糟。可能你應該看看你的模型/映射 - 對性能的改進可能在那裏。 – Pawel 2012-01-27 01:27:11

傢伙評論說，你必須把它在T-SQL重寫。真正。你可以嘗試SQL to LINQ converter tools之一。
還使用MS SQL Profiler來查看會發生什麼情況並提高TSQL性能。
嘗試添加索引but not too much :)

來源

2012-01-27 02:18:41

由ef生成的sql會立即執行。性能問題不在多個連接中，而在linq和生成的sql之間。數據庫也被編入索引，由ef生成的sql牆並沒有在Sql Management Studio中執行的問題（性能）。 – 2012-01-27 02:50:20

此查詢創建數據庫視圖和地圖視圖以新的只讀實體。之後，比較純LINQ執行和新執行之間的差異。如果問題在於將可怕的LINQ查詢轉換爲SQL，您將通過使用此方法來避免它。如果問題仍然緩慢，那麼問題將出現在其他地方。

來源

2012-01-27 08:56:52

問題是將LINQ查詢轉換爲sql。我寫了一個視圖，並將其映射到一個僅有的實體，並且查詢立即執行。 – 2012-01-29 06:09:05

實體框架遺漏加入永久（性能問題）

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