我有一个高度规范化的房地产数据库，用于存储列表数据。主要数据分布在3个表（Listings，ListingDataCommons和ListingDataOthers）之间，因为有大量的字段，因此有几个连接表可用于功能，类型等。
应用程序的用户使用GUI来定义条件/字段，系统将使用Where，Select和OrderBy语句生成（使用动态linq）。问题是当Select语句使用许多联结和/或查找表时，我得到Out Of Memory Exception。
下面是一个强类型（为了便于阅读）将抛出错误的查询示例。即使它只通过MLS号返回单个记录，它也会抛出OOM异常。
var ListingResult = context.Listings
.Where(a => a.MLSNumber == "123456" || a.MLSNumber == "654321")
.Select(a => new
{
//--- select some data from the Listings table
a.MLSNumber,
a.DateLastUpdated,
a.DateLastImageUpdated,
a.Address,
a.ZipCode,
a.DaysOnMarket,
a.DisplayOnInternet,
a.DisplayReviews,
a.AuctionYN,
a.ListPrice,
a.LeasePrice,
a.SystemID,
a.DateLastPriceChange,
a.DateLastStatusChange,
a.DisplayAddressOnlineYN,
a.ListingID,
Status = a.Status.Name,
PropertyType = a.PropertyType.Name,
PropertyStyle = a.PropertyStyle.Name,
Country = a.Country.Name,
State = a.State.Name,
County = a.County.Name,
City = a.City.Name,
SaleType = a.SaleType.Name,
//--- select some data from the ListingDataCommons table
BathsFull = a.ListingDataCommon.BathsFull,
BathsHalf = a.ListingDataCommon.BathsHalf,
Beds = a.ListingDataCommon.Beds,
FireplaceYN = a.ListingDataCommon.FireplaceYN,
GarageSpaces = a.ListingDataCommon.GarageSpaces,
HOAYN = a.ListingDataCommon.HOAYN,
LotAcres = a.ListingDataCommon.LotAcres,
NewConstructionYN = a.ListingDataCommon.NewConstructionYN,
PetsAllowedYN = a.ListingDataCommon.PetsAllowedYN,
PetsMaxWeight = a.ListingDataCommon.PetsMaxWeight,
PetsMaxNumber = a.ListingDataCommon.PetsMaxNumber,
RemarksPublic = a.ListingDataCommon.RemarksPublic,
SqftHeated = a.ListingDataCommon.SqftHeated,
SubdivisionName = a.ListingDataCommon.SubdivisionName,
Taxes = a.ListingDataCommon.Taxes,
TaxYear = a.ListingDataCommon.TaxYear,
YearBuilt = a.ListingDataCommon.YearBuilt,
AirConditioning = a.ListingDataCommon.AirConditioning.Name,
ConstructionStatus = a.ListingDataCommon.ConstructionStatus.Name,
HousingForOlder = a.ListingDataCommon.HousingForOlder.Name,
//--- select some data from the ListingDataOthers table
CDDFee = a.ListingDataOther.CDDFee,
CDDFeeYN = a.ListingDataOther.CDDFeeYN,
CondoFee = a.ListingDataOther.CondoFee,
HOAFee = a.ListingDataOther.HOAFee,
HomesteadYN = a.ListingDataOther.HomesteadYN,
LotDimensions = a.ListingDataOther.LotDimensions,
LotSqft = a.ListingDataOther.LotSqft,
NumberBays = a.ListingDataOther.NumberBays,
NumberBuildings = a.ListingDataOther.NumberBuildings,
NumberFloors = a.ListingDataOther.NumberFloors,
NumberHotelRooms = a.ListingDataOther.NumberHotelRooms,
NumberOffices = a.ListingDataOther.NumberOffices,
NumberRestrooms = a.ListingDataOther.NumberRestrooms,
ProjectedCompletionDate = a.ListingDataOther.ProjectedCompletionDate,
SchoolElementary = a.ListingDataOther.SchoolElementary,
SchoolMiddle = a.ListingDataOther.SchoolMiddle,
SchoolHigh = a.ListingDataOther.SchoolHigh,
SizePorch = a.ListingDataOther.SizePorch,
SizeBedMaster = a.ListingDataOther.SizeBedMaster,
SizeBed2 = a.ListingDataOther.SizeBed2,
SizeBed3 = a.ListingDataOther.SizeBed3,
SizeBed4 = a.ListingDataOther.SizeBed4,
SizeBed5 = a.ListingDataOther.SizeBed5,
SizeBonusRoom = a.ListingDataOther.SizeBonusRoom,
SizeDinette = a.ListingDataOther.SizeDinette,
SizeDiningRoom = a.ListingDataOther.SizeDiningRoom,
SizeFamilyRoom = a.ListingDataOther.SizeFamilyRoom,
SizeGreatRoom = a.ListingDataOther.SizeGreatRoom,
SizeKitchen = a.ListingDataOther.SizeKitchen,
SizeLivingRoom = a.ListingDataOther.SizeLivingRoom,
SizeStudio = a.ListingDataOther.SizeStudio,
SizeStudyDen = a.ListingDataOther.SizeStudyDen,
SqftTotalBldg = a.ListingDataOther.SqftTotalBldg,
TotalUnits = a.ListingDataOther.TotalUnits,
VirtualTourLink = a.ListingDataOther.VirtualTourLink,
WaterAccessYN = a.ListingDataOther.WaterAccessYN,
WaterExtrasYN = a.ListingDataOther.WaterExtrasYN,
WaterFrontageYN = a.ListingDataOther.WaterFrontageYN,
WaterViewYN = a.ListingDataOther.WaterViewYN,
ZipCodePlusFour = a.ListingDataOther.ZipCodePlusFour,
Zoning = a.ListingDataOther.Zoning,
AWCRemarks = a.ListingDataOther.AWCRemarks,
ArchitecturalStyle = a.ListingDataOther.ArchitecturalStyle.Name,
CondoFeeSchedule = a.ListingDataOther.TimeFrame.Name,
FrontExposure = a.ListingDataOther.FrontExposure.Name,
Foundation = a.ListingDataOther.Foundation.Name,
Furnishing = a.ListingDataOther.Furnishing.Name,
HOASchedule = a.ListingDataOther.TimeFrame.Name,
MobileHomeWidth = a.ListingDataOther.MobileHomeWidth.Name,
//--- select some data from the junction tables (which in turn use lookup tables)
AdditionalRooms = a.ListingAdditionalRooms.Select(b => b.AdditionalRoom.Name),
AppliancesIncluded = a.ListingAppliances.Select(b => b.Appliance.Name),
CommunityFeatures = a.ListingCommunityFeatures.Select(b => b.CommunityFeature.Name),
ExteriorConstructions = a.ListingExteriorConstructions.Select(b => b.ExteriorConstruction.Name),
ExteriorFeatures = a.ListingExteriorFeatures.Select(b => b.ExteriorFeature.Name),
Financings = a.ListingFinancings.Select(b => b.Financing.Name),
FireplaceDescriptions = a.ListingFireplaceDescriptions.Select(b => b.FireplaceDescription.Name),
FloorCoverings = a.ListingFloorCoverings.Select(b => b.FloorCovering.Name),
FuelTypes = a.ListingFuelTypes.Select(b => b.FuelType.Name),
GarageFeatures = a.ListingGarageFeatures.Select(b => b.GarageFeature.Name),
GarageTypes = a.ListingGarageTypes.Select(b => b.GarageType.Name),
HeatTypes = a.ListingHeatTypes.Select(b => b.HeatType.Name),
InteriorFeatures = a.ListingInteriorFeatures.Select(b => b.InteriorFeature.Name),
KitchenFeatures = a.ListingKitchenFeatures.Select(b => b.KitchenFeature.Name),
LeaseIncludes = a.ListingLeaseIncludes.Select(b => b.LeaseInclude.Name),
MasterBathFeatures = a.ListingMasterBathFeatures.Select(b => b.MasterBathFeature.Name),
ParkingOptions = a.ListingParkingOptions.Select(b => b.ParkingOption.Name),
PoolFeatures = a.ListingPoolFeatures.Select(b => b.PoolFeature.Name),
PoolTypes = a.ListingPoolTypes.Select(b => b.PoolType.Name),
PropertyUses = a.ListingPropertyUses.Select(b => b.PropertyUse.Name),
RoofTypes = a.ListingRoofTypes.Select(b => b.RoofType.Name),
WaterAccessTypes = a.ListingWaterAccessTypes.Select(b => b.WaterType.Name),
WaterExtraTypes = a.ListingWaterExtraTypes.Select(b => b.WaterExtraType.Name),
WaterFrontageTypes = a.ListingWaterFrontageTypes.Select(b => b.WaterType.Name),
WaterViewTypes = a.ListingWaterViewTypes.Select(b => b.WaterType.Name),
})
.OrderBy(a => a.MLSNumber)
.ToList();
这种结构有更好的方法吗？即使在查询上调用.ToString()来查看生成的SQL也会抛出OOM异常。
更新
在回应@Gert Arnold时，您能否进一步解释数据库未正常化的原因？我们以Status的字段为例，我有Status = a.Status.Name。数据库中有一个名为Statuses的表，其中包含2列StatusID和Name，数据类似于1|Active，2|Pending，{{1 }}。 3|Sold表上的字段为Listings，其中包含对StatusID表中StatusID字段的引用。为了获取实际名称而不是状态ID，我必须Statuses。这与PropertyType，PropertyStyle，Country，State，County，City，SaleType的结构完全相同。
然后，对于a.Status.Name和ListingDataCommons表，这些表与ListingDataOthers表的关系是1：1创建的。创建它们是因为列表中有数百个字段，而不是将它们转储到一个巨大的表中，它们根据每个字段的查询频率进行分割。在这些表中，有一些列引用了查找表的ID而不是重复的字符串值，如上面的状态所述。
然后有一些联结表，例如Listings，它具有1：多关系，其中1个列表可以有许多额外的房间。 ListingAdditionalRooms表（以及所有其他联结表）有2列（ListingID | AdditionalRoomID）引用ListingAdditionalRooms表和Listings表中的相应记录。
如果这是您已经看过的最糟糕的数据库设计之一，您如何建议对其进行改进？我应该有一个AdditionalRooms表，其中有近300列，通过记录重复存储字符串值吗？这似乎不是一个好的解决方案。请简要描述一下如何进行（Listings表有数百万条记录）。不要求图表，只是简单的解释。
对于建议，将其分解为更小的块并在2个请求中请求数据似乎确实解决了问题（一个请求中的联结表数据，另一个请求中的所有其他数据）。
关于此数据量从未在任何UI中显示，这是不正确的。虽然此查询仅测试限制，但绝对有必要向用户显示列表的完整详细信息。
我期待您对数据库结构的建议。
答案 0 :(得分：2)
实体框架在它必须生成的所有连接中窒息。只有在a.<some property>部分，您才能获得 35 不同的导航属性！最重要的是，您可以在嵌套的Select语句中访问大量导航属性。
核心问题是，这是迄今为止我见过的最糟糕的数据库设计之一。这些表只是大量不相关和重复的数据。没有任何规范化。
你唯一的希望是对数据模型进行重大改革，这是一种新的设计，基本上。实体框架是一个ORM，对象关系映射器，所以应该有一些关系来开始使它成为一个有用的工具。
如果设计不在您的手中，您可以考虑两件事：
获取内存中的数据逐个，并从这些构建块中构建客户端对象。
必须可以使用较小的模型。我无法想象有一个UI视图会一次显示所有这些数据。为每个视图构建专用视图模型。