एंटिटी फ्रेमवर्क पर एक और नज़र: प्रदर्शन और नुकसान

परिचय

डेटा मॉडल

 public class Account { public int Id { get; set; } [Required] public string Name { get; set; } } public class Message { public int Id { get; set; } public bool IsRead { get; set; } public DateTime Date { get; set; } public string Text { get; set; } [Required] public virtual MessageThread Thread { get; set; } [Required] public virtual Account Owner { get; set; } [Required] public virtual Account Sender { get; set; } [Required] public virtual Account Receiver { get; set; } } public class MessageThread { public int Id { get; set; } [Required] [StringLength(150)] public string Subject { get; set; } public virtual ICollection<MessageFolder> Folders { get; set; } } public class MessageFolder { public int Id { get; set; } public string Name { get; set; } [Required] public Account Owner { get; set; } public virtual ICollection<MessageThread> Threads { get; set; } } 

डेटा पढ़ना

 context.Messages.AsNoTracking().OrderBy(f => f.Id).Take(count) .Include(f => f.Owner).Include(f => f.Sender).Include(f => f.Receiver) .ToList(); 

 SELECT TOP (100) [Extent1].[Id] AS [Id], [Extent1].[IsRead] AS [IsRead], [Extent1].[Date] AS [Date], [Extent1].[Text] AS [Text], [Extent2].[Id] AS [Id1], [Extent2].[Name] AS [Name], [Extent3].[Id] AS [Id2], [Extent3].[Name] AS [Name1], [Extent4].[Id] AS [Id3], [Extent4].[Name] AS [Name2] FROM [dbo].[Message] AS [Extent1] INNER JOIN [dbo].[Account] AS [Extent2] ON [Extent1].[Owner_Id] = [Extent2].[Id] INNER JOIN [dbo].[Account] AS [Extent3] ON [Extent1].[Sender_Id] = [Extent3].[Id] INNER JOIN [dbo].[Account] AS [Extent4] ON [Extent1].[Receiver_Id] = [Extent4].[Id] ORDER BY [Extent1].[Id] ASC 

   IQueryable    ,  ,     ,   Linq2Entities,     .    (--)    . ,      extension methods  IQueryable   ,    . 
 
    Find   . Find      ,             .  ,    context.Messages.Find(1)   ,         .      . ,          . 
 context.Accounts.Load(); //     -    var m = context.Messages.First(); Console.WriteLine(m.Owner.Name); 
 SQL SELECT [Extent1].[Id] AS [Id], [Extent1].[Name] AS [Name] FROM [dbo].[Account] AS [Extent1] GO SELECT TOP (1) [c].[Id] AS [Id], [c].[IsRead] AS [IsRead], [c].[Date] AS [Date], [c].[Text] AS [Text], [c].[Thread_Id] AS [Thread_Id], [c].[Owner_Id] AS [Owner_Id], [c].[Sender_Id] AS [Sender_Id], [c].[Receiver_Id] AS [Receiver_Id] FROM [dbo].[Message] AS [c] 
   context.Messages.Include(f=>f.Owner).First()         . :    Include    SQL-,   . 
 
  ,     ,     ,       ,       context.Set().Local,      ,   .   SaveChanges .         .     Linq2Sql. 
 
   :        1000   EF   2-3  ,  Linq2Sql. , API   ,    Linq2Sql . 
 
   
     .     Add          Added .    SubmitChanges  ,      INSERT     .   navigation property,       ,     Added     (      ). 
 
    : 
       ValidateOnSaveEnabled  AutoDetectChangesEnabled .    .         .        ,         GC    .  ,      100 . 
      StackOverflow . 
    EF  ,     ( ) Linq2Sql. , ,     Linq2Sql. 
 
     
       .NET ORM-.      Bulk-. ,   SQL     , ORM    . 
 ,        .  EF     : 
 var messages = context.Messages.Where(f=>f.Thread.Id == threadId); foreach (var m in messages) m.IsRead = true; context.SaveChanges(); 
 SQL SELECT [Extent1].[Id] AS [Id], [Extent1].[IsRead] AS [IsRead], [Extent1].[Date] AS [Date], [Extent1].[Text] AS [Text], [Extent1].[Thread_Id] AS [Thread_Id], [Extent1].[Owner_Id] AS [Owner_Id], [Extent1].[Sender_Id] AS [Sender_Id], [Extent1].[Reciever_Id] AS [Reciever_Id] FROM [dbo].[Message] AS [Extent1] WHERE [Extent1].[Thread_Id] = @p__linq__0 update [dbo].[Message] set [IsRead] = @0 where ([Id] = @1) --(N ) 
 -,        ,         .   , ,   ,     –  .  ,     ,    .           . 
 
    update/delete   .    ,        . 
 
  EntityFramework.Extended       : 
 var messages = context.Messages.Where(f=>f.Thread.Id == threadId); messages.Update(f => new Message {IsRead = true}); 
 SQL UPDATE [dbo].[Message] SET [IsRead] = @p__update__0 FROM [dbo].[Message] AS j0 INNER JOIN ( SELECT [Extent1].[Id] AS [Id] FROM [dbo].[Message] AS [Extent1] WHERE [Extent1].[Thread_Id] = @p__linq__0 ) AS j1 ON (j0.[Id] = j1.[Id]) 
        .  ,    SaveChanges – SQL     .       ,       - ,     /. 
 
  ,      ,      dynamic         ( , ,  IntelliTrace),        .     (EntityFramework  ). 
   10 ,   10000 ,  EntityFramework 8 935 EntityFramework.Extended 28 83 
   ,  EntityFramework.Extended     ,      .    . 
 
   navigation property 
     –           . « !»       : 
 var count = folder.Threads.Count(); 
   ,   navigation properties,  ,     SQL. 
 SQL SELECT [Extent2].[Id] AS [Id], [Extent2].[Subject] AS [Subject] FROM [dbo].[ThreadsInFolders] AS [Extent1] INNER JOIN [dbo].[MessageThread] AS [Extent2] ON [Extent1].[MessageThread_Id] = [Extent2].[Id] WHERE [Extent1].[MessageFolder_Id] = @EntityKeyValue1 
   EF,   Linq2Sql,  Count() , Any() ,       ,   navigation property,        .   ,    «»  .  ,     ,  : 
 var count = context.Threads.Count(f => f.Folders.Any(e => e.Id == folder.Id))); 
 SQL SELECT [GroupBy1].[A1] AS [C1] FROM ( SELECT COUNT(1) AS [A1] FROM [dbo].[MessageThread] AS [Extent1] WHERE EXISTS (SELECT 1 AS [C1] FROM [dbo].[ThreadsInFolders] AS [Extent2] WHERE ([Extent1].[Id] = [Extent2].[MessageThread_Id]) AND ([Extent2].[MessageFolder_Id] = @p__linq__0) ) ) AS [GroupBy1] 
   ,      ,    , ,     ,  «  ». 
 
  
          –        ,   . 
 
     : 
 Response.Cache.SetLastModified(lastUpdated); 
  lastUpdated –    ,    . 
    ,  ASP.NET MVC       ToUniversalTime() ,     : 
 if (utcDate > DateTime.UtcNow) { throw new ArgumentOutOfRangeException("utcDate"); } 
     –    , DateTime    Kind        DateTimeKind.Undefined ( ,      ,      -  UTC   ).       ,   ,       (     DateTimeKind ),    ToUniversalTime()  ToLocalTime()         . ,         GMT - N. 
 
      EF,    Linq2Sql ,  ,   .     ,   code first  .      ObjectMaterialized     (    )      .        DateTime ,       ComplexType ,        reference type. 
 
 RequiredAttribute 
           EF. 
 
 ,      Owner , Sender , Receiver  Thread   Required . -,      ,       NOT NULL ,  -,      EF. 
 
 , -,           ? 
 var message = context.Messages.Find(1); message.IsRead = true; context.SaveChanges(); 
   ,       -  .  DbEntityValidationException . 
 
  RequiredAttribute   ,        null,        .  , ,  . 
 
   :      (),    (),  try-catch  SaveChanges      catch (),  ,   (),      RequiredAttribute   NOT NULL  Fluent API. , ,   ,         ,     ,           (  Required   null      UPDATE ).   ,         ,    . 
 
  (tl;dr) 
    EF  -       ?  .    ,  Microsoft      -            EF. 
 
   ,      EF      ,     ,     .    ,        ,             ,          EF. 
 
     EF    Linq2Sql? ,  , .          code first (    ),          .     ,     (   EF6 ).           -- (     ,         )  ..  ORM-    EF –  . 
 
     ,      ,    - Entity Framework.        // ,    .    . 

   IQueryable    ,  ,     ,   Linq2Entities,     .    (--)    . ,      extension methods  IQueryable   ,    . 
 
    Find   . Find      ,             .  ,    context.Messages.Find(1)   ,         .      . ,          . 
 context.Accounts.Load(); //     -    var m = context.Messages.First(); Console.WriteLine(m.Owner.Name); 
 SQL SELECT [Extent1].[Id] AS [Id], [Extent1].[Name] AS [Name] FROM [dbo].[Account] AS [Extent1] GO SELECT TOP (1) [c].[Id] AS [Id], [c].[IsRead] AS [IsRead], [c].[Date] AS [Date], [c].[Text] AS [Text], [c].[Thread_Id] AS [Thread_Id], [c].[Owner_Id] AS [Owner_Id], [c].[Sender_Id] AS [Sender_Id], [c].[Receiver_Id] AS [Receiver_Id] FROM [dbo].[Message] AS [c] 
   context.Messages.Include(f=>f.Owner).First()         . :    Include    SQL-,   . 
 
  ,     ,     ,       ,       context.Set().Local,      ,   .   SaveChanges .         .     Linq2Sql. 
 
   :        1000   EF   2-3  ,  Linq2Sql. , API   ,    Linq2Sql . 
 
   
     .     Add          Added .    SubmitChanges  ,      INSERT     .   navigation property,       ,     Added     (      ). 
 
    : 
       ValidateOnSaveEnabled  AutoDetectChangesEnabled .    .         .        ,         GC    .  ,      100 . 
      StackOverflow . 
    EF  ,     ( ) Linq2Sql. , ,     Linq2Sql. 
 
     
       .NET ORM-.      Bulk-. ,   SQL     , ORM    . 
 ,        .  EF     : 
 var messages = context.Messages.Where(f=>f.Thread.Id == threadId); foreach (var m in messages) m.IsRead = true; context.SaveChanges(); 
 SQL SELECT [Extent1].[Id] AS [Id], [Extent1].[IsRead] AS [IsRead], [Extent1].[Date] AS [Date], [Extent1].[Text] AS [Text], [Extent1].[Thread_Id] AS [Thread_Id], [Extent1].[Owner_Id] AS [Owner_Id], [Extent1].[Sender_Id] AS [Sender_Id], [Extent1].[Reciever_Id] AS [Reciever_Id] FROM [dbo].[Message] AS [Extent1] WHERE [Extent1].[Thread_Id] = @p__linq__0 update [dbo].[Message] set [IsRead] = @0 where ([Id] = @1) --(N ) 
 -,        ,         .   , ,   ,     –  .  ,     ,    .           . 
 
    update/delete   .    ,        . 
 
  EntityFramework.Extended       : 
 var messages = context.Messages.Where(f=>f.Thread.Id == threadId); messages.Update(f => new Message {IsRead = true}); 
 SQL UPDATE [dbo].[Message] SET [IsRead] = @p__update__0 FROM [dbo].[Message] AS j0 INNER JOIN ( SELECT [Extent1].[Id] AS [Id] FROM [dbo].[Message] AS [Extent1] WHERE [Extent1].[Thread_Id] = @p__linq__0 ) AS j1 ON (j0.[Id] = j1.[Id]) 
        .  ,    SaveChanges – SQL     .       ,       - ,     /. 
 
  ,      ,      dynamic         ( , ,  IntelliTrace),        .     (EntityFramework  ). 
   10 ,   10000 ,  EntityFramework 8 935 EntityFramework.Extended 28 83 
   ,  EntityFramework.Extended     ,      .    . 
 
   navigation property 
     –           . « !»       : 
 var count = folder.Threads.Count(); 
   ,   navigation properties,  ,     SQL. 
 SQL SELECT [Extent2].[Id] AS [Id], [Extent2].[Subject] AS [Subject] FROM [dbo].[ThreadsInFolders] AS [Extent1] INNER JOIN [dbo].[MessageThread] AS [Extent2] ON [Extent1].[MessageThread_Id] = [Extent2].[Id] WHERE [Extent1].[MessageFolder_Id] = @EntityKeyValue1 
   EF,   Linq2Sql,  Count() , Any() ,       ,   navigation property,        .   ,    «»  .  ,     ,  : 
 var count = context.Threads.Count(f => f.Folders.Any(e => e.Id == folder.Id))); 
 SQL SELECT [GroupBy1].[A1] AS [C1] FROM ( SELECT COUNT(1) AS [A1] FROM [dbo].[MessageThread] AS [Extent1] WHERE EXISTS (SELECT 1 AS [C1] FROM [dbo].[ThreadsInFolders] AS [Extent2] WHERE ([Extent1].[Id] = [Extent2].[MessageThread_Id]) AND ([Extent2].[MessageFolder_Id] = @p__linq__0) ) ) AS [GroupBy1] 
   ,      ,    , ,     ,  «  ». 
 
  
          –        ,   . 
 
     : 
 Response.Cache.SetLastModified(lastUpdated); 
  lastUpdated –    ,    . 
    ,  ASP.NET MVC       ToUniversalTime() ,     : 
 if (utcDate > DateTime.UtcNow) { throw new ArgumentOutOfRangeException("utcDate"); } 
     –    , DateTime    Kind        DateTimeKind.Undefined ( ,      ,      -  UTC   ).       ,   ,       (     DateTimeKind ),    ToUniversalTime()  ToLocalTime()         . ,         GMT - N. 
 
      EF,    Linq2Sql ,  ,   .     ,   code first  .      ObjectMaterialized     (    )      .        DateTime ,       ComplexType ,        reference type. 
 
 RequiredAttribute 
           EF. 
 
 ,      Owner , Sender , Receiver  Thread   Required . -,      ,       NOT NULL ,  -,      EF. 
 
 , -,           ? 
 var message = context.Messages.Find(1); message.IsRead = true; context.SaveChanges(); 
   ,       -  .  DbEntityValidationException . 
 
  RequiredAttribute   ,        null,        .  , ,  . 
 
   :      (),    (),  try-catch  SaveChanges      catch (),  ,   (),      RequiredAttribute   NOT NULL  Fluent API. , ,   ,         ,     ,           (  Required   null      UPDATE ).   ,         ,    . 
 
  (tl;dr) 
    EF  -       ?  .    ,  Microsoft      -            EF. 
 
   ,      EF      ,     ,     .    ,        ,             ,          EF. 
 
     EF    Linq2Sql? ,  , .          code first (    ),          .     ,     (   EF6 ).           -- (     ,         )  ..  ORM-    EF –  . 
 
     ,      ,    - Entity Framework.        // ,    .    . 

IQueryable , , , Linq2Entities, . (--) . , extension methods IQueryable , .

Find . Find , . , context.Messages.Find(1) , . . , .
context.Accounts.Load(); // - var m = context.Messages.First(); Console.WriteLine(m.Owner.Name);
SQL SELECT [Extent1].[Id] AS [Id], [Extent1].[Name] AS [Name] FROM [dbo].[Account] AS [Extent1] GO SELECT TOP (1) [c].[Id] AS [Id], [c].[IsRead] AS [IsRead], [c].[Date] AS [Date], [c].[Text] AS [Text], [c].[Thread_Id] AS [Thread_Id], [c].[Owner_Id] AS [Owner_Id], [c].[Sender_Id] AS [Sender_Id], [c].[Receiver_Id] AS [Receiver_Id] FROM [dbo].[Message] AS [c]
context.Messages.Include(f=>f.Owner).First() . : Include SQL-, .

, , , , context.Set().Local, , . SaveChanges . . Linq2Sql.

: 1000 EF 2-3 , Linq2Sql. , API , Linq2Sql .


. Add Added . SubmitChanges , INSERT . navigation property, , Added ( ).

:
ValidateOnSaveEnabled AutoDetectChangesEnabled . . . , GC . , 100 .
StackOverflow .
EF , ( ) Linq2Sql. , , Linq2Sql.


.NET ORM-. Bulk-. , SQL , ORM .
, . EF :
var messages = context.Messages.Where(f=>f.Thread.Id == threadId); foreach (var m in messages) m.IsRead = true; context.SaveChanges();
SQL SELECT [Extent1].[Id] AS [Id], [Extent1].[IsRead] AS [IsRead], [Extent1].[Date] AS [Date], [Extent1].[Text] AS [Text], [Extent1].[Thread_Id] AS [Thread_Id], [Extent1].[Owner_Id] AS [Owner_Id], [Extent1].[Sender_Id] AS [Sender_Id], [Extent1].[Reciever_Id] AS [Reciever_Id] FROM [dbo].[Message] AS [Extent1] WHERE [Extent1].[Thread_Id] = @p__linq__0 update [dbo].[Message] set [IsRead] = @0 where ([Id] = @1) --(N )
-, , . , , , – . , , . .

update/delete . , .

EntityFramework.Extended :
var messages = context.Messages.Where(f=>f.Thread.Id == threadId); messages.Update(f => new Message {IsRead = true});
SQL UPDATE [dbo].[Message] SET [IsRead] = @p__update__0 FROM [dbo].[Message] AS j0 INNER JOIN ( SELECT [Extent1].[Id] AS [Id] FROM [dbo].[Message] AS [Extent1] WHERE [Extent1].[Thread_Id] = @p__linq__0 ) AS j1 ON (j0.[Id] = j1.[Id])
. , SaveChanges – SQL . , - , /.

, , dynamic ( , , IntelliTrace), . (EntityFramework ).
10 , 10000 , EntityFramework 8 935 EntityFramework.Extended 28 83
, EntityFramework.Extended , . .

navigation property
– . « !» :
var count = folder.Threads.Count();
, navigation properties, , SQL.
SQL SELECT [Extent2].[Id] AS [Id], [Extent2].[Subject] AS [Subject] FROM [dbo].[ThreadsInFolders] AS [Extent1] INNER JOIN [dbo].[MessageThread] AS [Extent2] ON [Extent1].[MessageThread_Id] = [Extent2].[Id] WHERE [Extent1].[MessageFolder_Id] = @EntityKeyValue1
EF, Linq2Sql, Count() , Any() , , navigation property, . , «» . , , :
var count = context.Threads.Count(f => f.Folders.Any(e => e.Id == folder.Id)));
SQL SELECT [GroupBy1].[A1] AS [C1] FROM ( SELECT COUNT(1) AS [A1] FROM [dbo].[MessageThread] AS [Extent1] WHERE EXISTS (SELECT 1 AS [C1] FROM [dbo].[ThreadsInFolders] AS [Extent2] WHERE ([Extent1].[Id] = [Extent2].[MessageThread_Id]) AND ([Extent2].[MessageFolder_Id] = @p__linq__0) ) ) AS [GroupBy1]
, , , , , « ».


– , .

:
Response.Cache.SetLastModified(lastUpdated);
lastUpdated – , .
, ASP.NET MVC ToUniversalTime() , :
if (utcDate > DateTime.UtcNow) { throw new ArgumentOutOfRangeException("utcDate"); }
– , DateTime Kind DateTimeKind.Undefined ( , , - UTC ). , , ( DateTimeKind ), ToUniversalTime() ToLocalTime() . , GMT - N.

EF, Linq2Sql , , . , code first . ObjectMaterialized ( ) . DateTime , ComplexType , reference type.

RequiredAttribute
EF.

, Owner , Sender , Receiver Thread Required . -, , NOT NULL , -, EF.

, -, ?
var message = context.Messages.Find(1); message.IsRead = true; context.SaveChanges();
, - . DbEntityValidationException .

RequiredAttribute , null, . , , .

: (), (), try-catch SaveChanges catch (), , (), RequiredAttribute NOT NULL Fluent API. , , , , , ( Required null UPDATE ). , , .

(tl;dr)
EF - ? . , Microsoft - EF.

, EF , , . , , , EF.

EF Linq2Sql? , , . code first ( ), . , ( EF6 ). -- ( , ) .. ORM- EF – .

, , - Entity Framework. // , . .

1. IQueryable , , , Linq2Entities, . (--) . , extension methods IQueryable , .

Find . Find , . , context.Messages.Find(1) , . . , .
context.Accounts.Load(); // - var m = context.Messages.First(); Console.WriteLine(m.Owner.Name);
SQL SELECT [Extent1].[Id] AS [Id], [Extent1].[Name] AS [Name] FROM [dbo].[Account] AS [Extent1] GO SELECT TOP (1) [c].[Id] AS [Id], [c].[IsRead] AS [IsRead], [c].[Date] AS [Date], [c].[Text] AS [Text], [c].[Thread_Id] AS [Thread_Id], [c].[Owner_Id] AS [Owner_Id], [c].[Sender_Id] AS [Sender_Id], [c].[Receiver_Id] AS [Receiver_Id] FROM [dbo].[Message] AS [c]
context.Messages.Include(f=>f.Owner).First() . : Include SQL-, .

, , , , context.Set().Local, , . SaveChanges . . Linq2Sql.

: 1000 EF 2-3 , Linq2Sql. , API , Linq2Sql .


. Add Added . SubmitChanges , INSERT . navigation property, , Added ( ).

:
ValidateOnSaveEnabled AutoDetectChangesEnabled . . . , GC . , 100 .
StackOverflow .
EF , ( ) Linq2Sql. , , Linq2Sql.


.NET ORM-. Bulk-. , SQL , ORM .
, . EF :
var messages = context.Messages.Where(f=>f.Thread.Id == threadId); foreach (var m in messages) m.IsRead = true; context.SaveChanges();
SQL SELECT [Extent1].[Id] AS [Id], [Extent1].[IsRead] AS [IsRead], [Extent1].[Date] AS [Date], [Extent1].[Text] AS [Text], [Extent1].[Thread_Id] AS [Thread_Id], [Extent1].[Owner_Id] AS [Owner_Id], [Extent1].[Sender_Id] AS [Sender_Id], [Extent1].[Reciever_Id] AS [Reciever_Id] FROM [dbo].[Message] AS [Extent1] WHERE [Extent1].[Thread_Id] = @p__linq__0 update [dbo].[Message] set [IsRead] = @0 where ([Id] = @1) --(N )
-, , . , , , – . , , . .

update/delete . , .

EntityFramework.Extended :
var messages = context.Messages.Where(f=>f.Thread.Id == threadId); messages.Update(f => new Message {IsRead = true});
SQL UPDATE [dbo].[Message] SET [IsRead] = @p__update__0 FROM [dbo].[Message] AS j0 INNER JOIN ( SELECT [Extent1].[Id] AS [Id] FROM [dbo].[Message] AS [Extent1] WHERE [Extent1].[Thread_Id] = @p__linq__0 ) AS j1 ON (j0.[Id] = j1.[Id])
. , SaveChanges – SQL . , - , /.

, , dynamic ( , , IntelliTrace), . (EntityFramework ).
10 , 10000 , EntityFramework 8 935 EntityFramework.Extended 28 83
, EntityFramework.Extended , . .

navigation property
– . « !» :
var count = folder.Threads.Count();
, navigation properties, , SQL.
SQL SELECT [Extent2].[Id] AS [Id], [Extent2].[Subject] AS [Subject] FROM [dbo].[ThreadsInFolders] AS [Extent1] INNER JOIN [dbo].[MessageThread] AS [Extent2] ON [Extent1].[MessageThread_Id] = [Extent2].[Id] WHERE [Extent1].[MessageFolder_Id] = @EntityKeyValue1
EF, Linq2Sql, Count() , Any() , , navigation property, . , «» . , , :
var count = context.Threads.Count(f => f.Folders.Any(e => e.Id == folder.Id)));
SQL SELECT [GroupBy1].[A1] AS [C1] FROM ( SELECT COUNT(1) AS [A1] FROM [dbo].[MessageThread] AS [Extent1] WHERE EXISTS (SELECT 1 AS [C1] FROM [dbo].[ThreadsInFolders] AS [Extent2] WHERE ([Extent1].[Id] = [Extent2].[MessageThread_Id]) AND ([Extent2].[MessageFolder_Id] = @p__linq__0) ) ) AS [GroupBy1]
, , , , , « ».


– , .

:
Response.Cache.SetLastModified(lastUpdated);
lastUpdated – , .
, ASP.NET MVC ToUniversalTime() , :
if (utcDate > DateTime.UtcNow) { throw new ArgumentOutOfRangeException("utcDate"); }
– , DateTime Kind DateTimeKind.Undefined ( , , - UTC ). , , ( DateTimeKind ), ToUniversalTime() ToLocalTime() . , GMT - N.

EF, Linq2Sql , , . , code first . ObjectMaterialized ( ) . DateTime , ComplexType , reference type.

RequiredAttribute
EF.

, Owner , Sender , Receiver Thread Required . -, , NOT NULL , -, EF.

, -, ?
var message = context.Messages.Find(1); message.IsRead = true; context.SaveChanges();
, - . DbEntityValidationException .

RequiredAttribute , null, . , , .

: (), (), try-catch SaveChanges catch (), , (), RequiredAttribute NOT NULL Fluent API. , , , , , ( Required null UPDATE ). , , .

(tl;dr)
EF - ? . , Microsoft - EF.

, EF , , . , , , EF.

EF Linq2Sql? , , . code first ( ), . , ( EF6 ). -- ( , ) .. ORM- EF – .

, , - Entity Framework. // , . .
2. IQueryable , , , Linq2Entities, . (--) . , extension methods IQueryable , .

Find . Find , . , context.Messages.Find(1) , . . , .
context.Accounts.Load(); // - var m = context.Messages.First(); Console.WriteLine(m.Owner.Name);
SQL SELECT [Extent1].[Id] AS [Id], [Extent1].[Name] AS [Name] FROM [dbo].[Account] AS [Extent1] GO SELECT TOP (1) [c].[Id] AS [Id], [c].[IsRead] AS [IsRead], [c].[Date] AS [Date], [c].[Text] AS [Text], [c].[Thread_Id] AS [Thread_Id], [c].[Owner_Id] AS [Owner_Id], [c].[Sender_Id] AS [Sender_Id], [c].[Receiver_Id] AS [Receiver_Id] FROM [dbo].[Message] AS [c]
context.Messages.Include(f=>f.Owner).First() . : Include SQL-, .

, , , , context.Set().Local, , . SaveChanges . . Linq2Sql.

: 1000 EF 2-3 , Linq2Sql. , API , Linq2Sql .


. Add Added . SubmitChanges , INSERT . navigation property, , Added ( ).

:
ValidateOnSaveEnabled AutoDetectChangesEnabled . . . , GC . , 100 .
StackOverflow .
EF , ( ) Linq2Sql. , , Linq2Sql.


.NET ORM-. Bulk-. , SQL , ORM .
, . EF :
var messages = context.Messages.Where(f=>f.Thread.Id == threadId); foreach (var m in messages) m.IsRead = true; context.SaveChanges();
SQL SELECT [Extent1].[Id] AS [Id], [Extent1].[IsRead] AS [IsRead], [Extent1].[Date] AS [Date], [Extent1].[Text] AS [Text], [Extent1].[Thread_Id] AS [Thread_Id], [Extent1].[Owner_Id] AS [Owner_Id], [Extent1].[Sender_Id] AS [Sender_Id], [Extent1].[Reciever_Id] AS [Reciever_Id] FROM [dbo].[Message] AS [Extent1] WHERE [Extent1].[Thread_Id] = @p__linq__0 update [dbo].[Message] set [IsRead] = @0 where ([Id] = @1) --(N )
-, , . , , , – . , , . .

update/delete . , .

EntityFramework.Extended :
var messages = context.Messages.Where(f=>f.Thread.Id == threadId); messages.Update(f => new Message {IsRead = true});
SQL UPDATE [dbo].[Message] SET [IsRead] = @p__update__0 FROM [dbo].[Message] AS j0 INNER JOIN ( SELECT [Extent1].[Id] AS [Id] FROM [dbo].[Message] AS [Extent1] WHERE [Extent1].[Thread_Id] = @p__linq__0 ) AS j1 ON (j0.[Id] = j1.[Id])
. , SaveChanges – SQL . , - , /.

, , dynamic ( , , IntelliTrace), . (EntityFramework ).
10 , 10000 , EntityFramework 8 935 EntityFramework.Extended 28 83
, EntityFramework.Extended , . .

navigation property
– . « !» :
var count = folder.Threads.Count();
, navigation properties, , SQL.
SQL SELECT [Extent2].[Id] AS [Id], [Extent2].[Subject] AS [Subject] FROM [dbo].[ThreadsInFolders] AS [Extent1] INNER JOIN [dbo].[MessageThread] AS [Extent2] ON [Extent1].[MessageThread_Id] = [Extent2].[Id] WHERE [Extent1].[MessageFolder_Id] = @EntityKeyValue1
EF, Linq2Sql, Count() , Any() , , navigation property, . , «» . , , :
var count = context.Threads.Count(f => f.Folders.Any(e => e.Id == folder.Id)));
SQL SELECT [GroupBy1].[A1] AS [C1] FROM ( SELECT COUNT(1) AS [A1] FROM [dbo].[MessageThread] AS [Extent1] WHERE EXISTS (SELECT 1 AS [C1] FROM [dbo].[ThreadsInFolders] AS [Extent2] WHERE ([Extent1].[Id] = [Extent2].[MessageThread_Id]) AND ([Extent2].[MessageFolder_Id] = @p__linq__0) ) ) AS [GroupBy1]
, , , , , « ».


– , .

:
Response.Cache.SetLastModified(lastUpdated);
lastUpdated – , .
, ASP.NET MVC ToUniversalTime() , :
if (utcDate > DateTime.UtcNow) { throw new ArgumentOutOfRangeException("utcDate"); }
– , DateTime Kind DateTimeKind.Undefined ( , , - UTC ). , , ( DateTimeKind ), ToUniversalTime() ToLocalTime() . , GMT - N.

EF, Linq2Sql , , . , code first . ObjectMaterialized ( ) . DateTime , ComplexType , reference type.

RequiredAttribute
EF.

, Owner , Sender , Receiver Thread Required . -, , NOT NULL , -, EF.

, -, ?
var message = context.Messages.Find(1); message.IsRead = true; context.SaveChanges();
, - . DbEntityValidationException .

RequiredAttribute , null, . , , .

: (), (), try-catch SaveChanges catch (), , (), RequiredAttribute NOT NULL Fluent API. , , , , , ( Required null UPDATE ). , , .

(tl;dr)
EF - ? . , Microsoft - EF.

, EF , , . , , , EF.

EF Linq2Sql? , , . code first ( ), . , ( EF6 ). -- ( , ) .. ORM- EF – .

, , - Entity Framework. // , . .

IQueryable , , , Linq2Entities, . (--) . , extension methods IQueryable , .

Find . Find , . , context.Messages.Find(1) , . . , .
context.Accounts.Load(); // - var m = context.Messages.First(); Console.WriteLine(m.Owner.Name);
SQL SELECT [Extent1].[Id] AS [Id], [Extent1].[Name] AS [Name] FROM [dbo].[Account] AS [Extent1] GO SELECT TOP (1) [c].[Id] AS [Id], [c].[IsRead] AS [IsRead], [c].[Date] AS [Date], [c].[Text] AS [Text], [c].[Thread_Id] AS [Thread_Id], [c].[Owner_Id] AS [Owner_Id], [c].[Sender_Id] AS [Sender_Id], [c].[Receiver_Id] AS [Receiver_Id] FROM [dbo].[Message] AS [c]
context.Messages.Include(f=>f.Owner).First() . : Include SQL-, .

, , , , context.Set().Local, , . SaveChanges . . Linq2Sql.

: 1000 EF 2-3 , Linq2Sql. , API , Linq2Sql .


. Add Added . SubmitChanges , INSERT . navigation property, , Added ( ).

:
ValidateOnSaveEnabled AutoDetectChangesEnabled . . . , GC . , 100 .
StackOverflow .
EF , ( ) Linq2Sql. , , Linq2Sql.


.NET ORM-. Bulk-. , SQL , ORM .
, . EF :
var messages = context.Messages.Where(f=>f.Thread.Id == threadId); foreach (var m in messages) m.IsRead = true; context.SaveChanges();
SQL SELECT [Extent1].[Id] AS [Id], [Extent1].[IsRead] AS [IsRead], [Extent1].[Date] AS [Date], [Extent1].[Text] AS [Text], [Extent1].[Thread_Id] AS [Thread_Id], [Extent1].[Owner_Id] AS [Owner_Id], [Extent1].[Sender_Id] AS [Sender_Id], [Extent1].[Reciever_Id] AS [Reciever_Id] FROM [dbo].[Message] AS [Extent1] WHERE [Extent1].[Thread_Id] = @p__linq__0 update [dbo].[Message] set [IsRead] = @0 where ([Id] = @1) --(N )
-, , . , , , – . , , . .

update/delete . , .

EntityFramework.Extended :
var messages = context.Messages.Where(f=>f.Thread.Id == threadId); messages.Update(f => new Message {IsRead = true});
SQL UPDATE [dbo].[Message] SET [IsRead] = @p__update__0 FROM [dbo].[Message] AS j0 INNER JOIN ( SELECT [Extent1].[Id] AS [Id] FROM [dbo].[Message] AS [Extent1] WHERE [Extent1].[Thread_Id] = @p__linq__0 ) AS j1 ON (j0.[Id] = j1.[Id])
. , SaveChanges – SQL . , - , /.

, , dynamic ( , , IntelliTrace), . (EntityFramework ).
10 , 10000 , EntityFramework 8 935 EntityFramework.Extended 28 83
, EntityFramework.Extended , . .

navigation property
– . « !» :
var count = folder.Threads.Count();
, navigation properties, , SQL.
SQL SELECT [Extent2].[Id] AS [Id], [Extent2].[Subject] AS [Subject] FROM [dbo].[ThreadsInFolders] AS [Extent1] INNER JOIN [dbo].[MessageThread] AS [Extent2] ON [Extent1].[MessageThread_Id] = [Extent2].[Id] WHERE [Extent1].[MessageFolder_Id] = @EntityKeyValue1
EF, Linq2Sql, Count() , Any() , , navigation property, . , «» . , , :
var count = context.Threads.Count(f => f.Folders.Any(e => e.Id == folder.Id)));
SQL SELECT [GroupBy1].[A1] AS [C1] FROM ( SELECT COUNT(1) AS [A1] FROM [dbo].[MessageThread] AS [Extent1] WHERE EXISTS (SELECT 1 AS [C1] FROM [dbo].[ThreadsInFolders] AS [Extent2] WHERE ([Extent1].[Id] = [Extent2].[MessageThread_Id]) AND ([Extent2].[MessageFolder_Id] = @p__linq__0) ) ) AS [GroupBy1]
, , , , , « ».


– , .

:
Response.Cache.SetLastModified(lastUpdated);
lastUpdated – , .
, ASP.NET MVC ToUniversalTime() , :
if (utcDate > DateTime.UtcNow) { throw new ArgumentOutOfRangeException("utcDate"); }
– , DateTime Kind DateTimeKind.Undefined ( , , - UTC ). , , ( DateTimeKind ), ToUniversalTime() ToLocalTime() . , GMT - N.

EF, Linq2Sql , , . , code first . ObjectMaterialized ( ) . DateTime , ComplexType , reference type.

RequiredAttribute
EF.

, Owner , Sender , Receiver Thread Required . -, , NOT NULL , -, EF.

, -, ?
var message = context.Messages.Find(1); message.IsRead = true; context.SaveChanges();
, - . DbEntityValidationException .

RequiredAttribute , null, . , , .

: (), (), try-catch SaveChanges catch (), , (), RequiredAttribute NOT NULL Fluent API. , , , , , ( Required null UPDATE ). , , .

(tl;dr)
EF - ? . , Microsoft - EF.

, EF , , . , , , EF.

EF Linq2Sql? , , . code first ( ), . , ( EF6 ). -- ( , ) .. ORM- EF – .

, , - Entity Framework. // , . .

   IQueryable    ,  ,     ,   Linq2Entities,     .    (--)    . ,      extension methods  IQueryable   ,    . 
 
    Find   . Find      ,             .  ,    context.Messages.Find(1)   ,         .      . ,          . 
 context.Accounts.Load(); //     -    var m = context.Messages.First(); Console.WriteLine(m.Owner.Name); 
 SQL SELECT [Extent1].[Id] AS [Id], [Extent1].[Name] AS [Name] FROM [dbo].[Account] AS [Extent1] GO SELECT TOP (1) [c].[Id] AS [Id], [c].[IsRead] AS [IsRead], [c].[Date] AS [Date], [c].[Text] AS [Text], [c].[Thread_Id] AS [Thread_Id], [c].[Owner_Id] AS [Owner_Id], [c].[Sender_Id] AS [Sender_Id], [c].[Receiver_Id] AS [Receiver_Id] FROM [dbo].[Message] AS [c] 
   context.Messages.Include(f=>f.Owner).First()         . :    Include    SQL-,   . 
 
  ,     ,     ,       ,       context.Set().Local,      ,   .   SaveChanges .         .     Linq2Sql. 
 
   :        1000   EF   2-3  ,  Linq2Sql. , API   ,    Linq2Sql . 
 
   
     .     Add          Added .    SubmitChanges  ,      INSERT     .   navigation property,       ,     Added     (      ). 
 
    : 
       ValidateOnSaveEnabled  AutoDetectChangesEnabled .    .         .        ,         GC    .  ,      100 . 
      StackOverflow . 
    EF  ,     ( ) Linq2Sql. , ,     Linq2Sql. 
 
     
       .NET ORM-.      Bulk-. ,   SQL     , ORM    . 
 ,        .  EF     : 
 var messages = context.Messages.Where(f=>f.Thread.Id == threadId); foreach (var m in messages) m.IsRead = true; context.SaveChanges(); 
 SQL SELECT [Extent1].[Id] AS [Id], [Extent1].[IsRead] AS [IsRead], [Extent1].[Date] AS [Date], [Extent1].[Text] AS [Text], [Extent1].[Thread_Id] AS [Thread_Id], [Extent1].[Owner_Id] AS [Owner_Id], [Extent1].[Sender_Id] AS [Sender_Id], [Extent1].[Reciever_Id] AS [Reciever_Id] FROM [dbo].[Message] AS [Extent1] WHERE [Extent1].[Thread_Id] = @p__linq__0 update [dbo].[Message] set [IsRead] = @0 where ([Id] = @1) --(N ) 
 -,        ,         .   , ,   ,     –  .  ,     ,    .           . 
 
    update/delete   .    ,        . 
 
  EntityFramework.Extended       : 
 var messages = context.Messages.Where(f=>f.Thread.Id == threadId); messages.Update(f => new Message {IsRead = true}); 
 SQL UPDATE [dbo].[Message] SET [IsRead] = @p__update__0 FROM [dbo].[Message] AS j0 INNER JOIN ( SELECT [Extent1].[Id] AS [Id] FROM [dbo].[Message] AS [Extent1] WHERE [Extent1].[Thread_Id] = @p__linq__0 ) AS j1 ON (j0.[Id] = j1.[Id]) 
        .  ,    SaveChanges – SQL     .       ,       - ,     /. 
 
  ,      ,      dynamic         ( , ,  IntelliTrace),        .     (EntityFramework  ). 
   10 ,   10000 ,  EntityFramework 8 935 EntityFramework.Extended 28 83 
   ,  EntityFramework.Extended     ,      .    . 
 
   navigation property 
     –           . « !»       : 
 var count = folder.Threads.Count(); 
   ,   navigation properties,  ,     SQL. 
 SQL SELECT [Extent2].[Id] AS [Id], [Extent2].[Subject] AS [Subject] FROM [dbo].[ThreadsInFolders] AS [Extent1] INNER JOIN [dbo].[MessageThread] AS [Extent2] ON [Extent1].[MessageThread_Id] = [Extent2].[Id] WHERE [Extent1].[MessageFolder_Id] = @EntityKeyValue1 
   EF,   Linq2Sql,  Count() , Any() ,       ,   navigation property,        .   ,    «»  .  ,     ,  : 
 var count = context.Threads.Count(f => f.Folders.Any(e => e.Id == folder.Id))); 
 SQL SELECT [GroupBy1].[A1] AS [C1] FROM ( SELECT COUNT(1) AS [A1] FROM [dbo].[MessageThread] AS [Extent1] WHERE EXISTS (SELECT 1 AS [C1] FROM [dbo].[ThreadsInFolders] AS [Extent2] WHERE ([Extent1].[Id] = [Extent2].[MessageThread_Id]) AND ([Extent2].[MessageFolder_Id] = @p__linq__0) ) ) AS [GroupBy1] 
   ,      ,    , ,     ,  «  ». 
 
  
          –        ,   . 
 
     : 
 Response.Cache.SetLastModified(lastUpdated); 
  lastUpdated –    ,    . 
    ,  ASP.NET MVC       ToUniversalTime() ,     : 
 if (utcDate > DateTime.UtcNow) { throw new ArgumentOutOfRangeException("utcDate"); } 
     –    , DateTime    Kind        DateTimeKind.Undefined ( ,      ,      -  UTC   ).       ,   ,       (     DateTimeKind ),    ToUniversalTime()  ToLocalTime()         . ,         GMT - N. 
 
      EF,    Linq2Sql ,  ,   .     ,   code first  .      ObjectMaterialized     (    )      .        DateTime ,       ComplexType ,        reference type. 
 
 RequiredAttribute 
           EF. 
 
 ,      Owner , Sender , Receiver  Thread   Required . -,      ,       NOT NULL ,  -,      EF. 
 
 , -,           ? 
 var message = context.Messages.Find(1); message.IsRead = true; context.SaveChanges(); 
   ,       -  .  DbEntityValidationException . 
 
  RequiredAttribute   ,        null,        .  , ,  . 
 
   :      (),    (),  try-catch  SaveChanges      catch (),  ,   (),      RequiredAttribute   NOT NULL  Fluent API. , ,   ,         ,     ,           (  Required   null      UPDATE ).   ,         ,    . 
 
  (tl;dr) 
    EF  -       ?  .    ,  Microsoft      -            EF. 
 
   ,      EF      ,     ,     .    ,        ,             ,          EF. 
 
     EF    Linq2Sql? ,  , .          code first (    ),          .     ,     (   EF6 ).           -- (     ,         )  ..  ORM-    EF –  . 
 
     ,      ,    - Entity Framework.        // ,    .    . 

   IQueryable    ,  ,     ,   Linq2Entities,     .    (--)    . ,      extension methods  IQueryable   ,    . 
 
    Find   . Find      ,             .  ,    context.Messages.Find(1)   ,         .      . ,          . 
 context.Accounts.Load(); //     -    var m = context.Messages.First(); Console.WriteLine(m.Owner.Name); 
 SQL SELECT [Extent1].[Id] AS [Id], [Extent1].[Name] AS [Name] FROM [dbo].[Account] AS [Extent1] GO SELECT TOP (1) [c].[Id] AS [Id], [c].[IsRead] AS [IsRead], [c].[Date] AS [Date], [c].[Text] AS [Text], [c].[Thread_Id] AS [Thread_Id], [c].[Owner_Id] AS [Owner_Id], [c].[Sender_Id] AS [Sender_Id], [c].[Receiver_Id] AS [Receiver_Id] FROM [dbo].[Message] AS [c] 
   context.Messages.Include(f=>f.Owner).First()         . :    Include    SQL-,   . 
 
  ,     ,     ,       ,       context.Set().Local,      ,   .   SaveChanges .         .     Linq2Sql. 
 
   :        1000   EF   2-3  ,  Linq2Sql. , API   ,    Linq2Sql . 
 
   
     .     Add          Added .    SubmitChanges  ,      INSERT     .   navigation property,       ,     Added     (      ). 
 
    : 
       ValidateOnSaveEnabled  AutoDetectChangesEnabled .    .         .        ,         GC    .  ,      100 . 
      StackOverflow . 
    EF  ,     ( ) Linq2Sql. , ,     Linq2Sql. 
 
     
       .NET ORM-.      Bulk-. ,   SQL     , ORM    . 
 ,        .  EF     : 
 var messages = context.Messages.Where(f=>f.Thread.Id == threadId); foreach (var m in messages) m.IsRead = true; context.SaveChanges(); 
 SQL SELECT [Extent1].[Id] AS [Id], [Extent1].[IsRead] AS [IsRead], [Extent1].[Date] AS [Date], [Extent1].[Text] AS [Text], [Extent1].[Thread_Id] AS [Thread_Id], [Extent1].[Owner_Id] AS [Owner_Id], [Extent1].[Sender_Id] AS [Sender_Id], [Extent1].[Reciever_Id] AS [Reciever_Id] FROM [dbo].[Message] AS [Extent1] WHERE [Extent1].[Thread_Id] = @p__linq__0 update [dbo].[Message] set [IsRead] = @0 where ([Id] = @1) --(N ) 
 -,        ,         .   , ,   ,     –  .  ,     ,    .           . 
 
    update/delete   .    ,        . 
 
  EntityFramework.Extended       : 
 var messages = context.Messages.Where(f=>f.Thread.Id == threadId); messages.Update(f => new Message {IsRead = true}); 
 SQL UPDATE [dbo].[Message] SET [IsRead] = @p__update__0 FROM [dbo].[Message] AS j0 INNER JOIN ( SELECT [Extent1].[Id] AS [Id] FROM [dbo].[Message] AS [Extent1] WHERE [Extent1].[Thread_Id] = @p__linq__0 ) AS j1 ON (j0.[Id] = j1.[Id]) 
        .  ,    SaveChanges – SQL     .       ,       - ,     /. 
 
  ,      ,      dynamic         ( , ,  IntelliTrace),        .     (EntityFramework  ). 
   10 ,   10000 ,  EntityFramework 8 935 EntityFramework.Extended 28 83 
   ,  EntityFramework.Extended     ,      .    . 
 
   navigation property 
     –           . « !»       : 
 var count = folder.Threads.Count(); 
   ,   navigation properties,  ,     SQL. 
 SQL SELECT [Extent2].[Id] AS [Id], [Extent2].[Subject] AS [Subject] FROM [dbo].[ThreadsInFolders] AS [Extent1] INNER JOIN [dbo].[MessageThread] AS [Extent2] ON [Extent1].[MessageThread_Id] = [Extent2].[Id] WHERE [Extent1].[MessageFolder_Id] = @EntityKeyValue1 
   EF,   Linq2Sql,  Count() , Any() ,       ,   navigation property,        .   ,    «»  .  ,     ,  : 
 var count = context.Threads.Count(f => f.Folders.Any(e => e.Id == folder.Id))); 
 SQL SELECT [GroupBy1].[A1] AS [C1] FROM ( SELECT COUNT(1) AS [A1] FROM [dbo].[MessageThread] AS [Extent1] WHERE EXISTS (SELECT 1 AS [C1] FROM [dbo].[ThreadsInFolders] AS [Extent2] WHERE ([Extent1].[Id] = [Extent2].[MessageThread_Id]) AND ([Extent2].[MessageFolder_Id] = @p__linq__0) ) ) AS [GroupBy1] 
   ,      ,    , ,     ,  «  ». 
 
  
          –        ,   . 
 
     : 
 Response.Cache.SetLastModified(lastUpdated); 
  lastUpdated –    ,    . 
    ,  ASP.NET MVC       ToUniversalTime() ,     : 
 if (utcDate > DateTime.UtcNow) { throw new ArgumentOutOfRangeException("utcDate"); } 
     –    , DateTime    Kind        DateTimeKind.Undefined ( ,      ,      -  UTC   ).       ,   ,       (     DateTimeKind ),    ToUniversalTime()  ToLocalTime()         . ,         GMT - N. 
 
      EF,    Linq2Sql ,  ,   .     ,   code first  .      ObjectMaterialized     (    )      .        DateTime ,       ComplexType ,        reference type. 
 
 RequiredAttribute 
           EF. 
 
 ,      Owner , Sender , Receiver  Thread   Required . -,      ,       NOT NULL ,  -,      EF. 
 
 , -,           ? 
 var message = context.Messages.Find(1); message.IsRead = true; context.SaveChanges(); 
   ,       -  .  DbEntityValidationException . 
 
  RequiredAttribute   ,        null,        .  , ,  . 
 
   :      (),    (),  try-catch  SaveChanges      catch (),  ,   (),      RequiredAttribute   NOT NULL  Fluent API. , ,   ,         ,     ,           (  Required   null      UPDATE ).   ,         ,    . 
 
  (tl;dr) 
    EF  -       ?  .    ,  Microsoft      -            EF. 
 
   ,      EF      ,     ,     .    ,        ,             ,          EF. 
 
     EF    Linq2Sql? ,  , .          code first (    ),          .     ,     (   EF6 ).           -- (     ,         )  ..  ORM-    EF –  . 
 
     ,      ,    - Entity Framework.        // ,    .    . 

   IQueryable    ,  ,     ,   Linq2Entities,     .    (--)    . ,      extension methods  IQueryable   ,    . 
 
    Find   . Find      ,             .  ,    context.Messages.Find(1)   ,         .      . ,          . 
 context.Accounts.Load(); //     -    var m = context.Messages.First(); Console.WriteLine(m.Owner.Name); 
 SQL SELECT [Extent1].[Id] AS [Id], [Extent1].[Name] AS [Name] FROM [dbo].[Account] AS [Extent1] GO SELECT TOP (1) [c].[Id] AS [Id], [c].[IsRead] AS [IsRead], [c].[Date] AS [Date], [c].[Text] AS [Text], [c].[Thread_Id] AS [Thread_Id], [c].[Owner_Id] AS [Owner_Id], [c].[Sender_Id] AS [Sender_Id], [c].[Receiver_Id] AS [Receiver_Id] FROM [dbo].[Message] AS [c] 
   context.Messages.Include(f=>f.Owner).First()         . :    Include    SQL-,   . 
 
  ,     ,     ,       ,       context.Set().Local,      ,   .   SaveChanges .         .     Linq2Sql. 
 
   :        1000   EF   2-3  ,  Linq2Sql. , API   ,    Linq2Sql . 
 
   
     .     Add          Added .    SubmitChanges  ,      INSERT     .   navigation property,       ,     Added     (      ). 
 
    : 
       ValidateOnSaveEnabled  AutoDetectChangesEnabled .    .         .        ,         GC    .  ,      100 . 
      StackOverflow . 
    EF  ,     ( ) Linq2Sql. , ,     Linq2Sql. 
 
     
       .NET ORM-.      Bulk-. ,   SQL     , ORM    . 
 ,        .  EF     : 
 var messages = context.Messages.Where(f=>f.Thread.Id == threadId); foreach (var m in messages) m.IsRead = true; context.SaveChanges(); 
 SQL SELECT [Extent1].[Id] AS [Id], [Extent1].[IsRead] AS [IsRead], [Extent1].[Date] AS [Date], [Extent1].[Text] AS [Text], [Extent1].[Thread_Id] AS [Thread_Id], [Extent1].[Owner_Id] AS [Owner_Id], [Extent1].[Sender_Id] AS [Sender_Id], [Extent1].[Reciever_Id] AS [Reciever_Id] FROM [dbo].[Message] AS [Extent1] WHERE [Extent1].[Thread_Id] = @p__linq__0 update [dbo].[Message] set [IsRead] = @0 where ([Id] = @1) --(N ) 
 -,        ,         .   , ,   ,     –  .  ,     ,    .           . 
 
    update/delete   .    ,        . 
 
  EntityFramework.Extended       : 
 var messages = context.Messages.Where(f=>f.Thread.Id == threadId); messages.Update(f => new Message {IsRead = true}); 
 SQL UPDATE [dbo].[Message] SET [IsRead] = @p__update__0 FROM [dbo].[Message] AS j0 INNER JOIN ( SELECT [Extent1].[Id] AS [Id] FROM [dbo].[Message] AS [Extent1] WHERE [Extent1].[Thread_Id] = @p__linq__0 ) AS j1 ON (j0.[Id] = j1.[Id]) 
        .  ,    SaveChanges – SQL     .       ,       - ,     /. 
 
  ,      ,      dynamic         ( , ,  IntelliTrace),        .     (EntityFramework  ). 
   10 ,   10000 ,  EntityFramework 8 935 EntityFramework.Extended 28 83 
   ,  EntityFramework.Extended     ,      .    . 
 
   navigation property 
     –           . « !»       : 
 var count = folder.Threads.Count(); 
   ,   navigation properties,  ,     SQL. 
 SQL SELECT [Extent2].[Id] AS [Id], [Extent2].[Subject] AS [Subject] FROM [dbo].[ThreadsInFolders] AS [Extent1] INNER JOIN [dbo].[MessageThread] AS [Extent2] ON [Extent1].[MessageThread_Id] = [Extent2].[Id] WHERE [Extent1].[MessageFolder_Id] = @EntityKeyValue1 
   EF,   Linq2Sql,  Count() , Any() ,       ,   navigation property,        .   ,    «»  .  ,     ,  : 
 var count = context.Threads.Count(f => f.Folders.Any(e => e.Id == folder.Id))); 
 SQL SELECT [GroupBy1].[A1] AS [C1] FROM ( SELECT COUNT(1) AS [A1] FROM [dbo].[MessageThread] AS [Extent1] WHERE EXISTS (SELECT 1 AS [C1] FROM [dbo].[ThreadsInFolders] AS [Extent2] WHERE ([Extent1].[Id] = [Extent2].[MessageThread_Id]) AND ([Extent2].[MessageFolder_Id] = @p__linq__0) ) ) AS [GroupBy1] 
   ,      ,    , ,     ,  «  ». 
 
  
          –        ,   . 
 
     : 
 Response.Cache.SetLastModified(lastUpdated); 
  lastUpdated –    ,    . 
    ,  ASP.NET MVC       ToUniversalTime() ,     : 
 if (utcDate > DateTime.UtcNow) { throw new ArgumentOutOfRangeException("utcDate"); } 
     –    , DateTime    Kind        DateTimeKind.Undefined ( ,      ,      -  UTC   ).       ,   ,       (     DateTimeKind ),    ToUniversalTime()  ToLocalTime()         . ,         GMT - N. 
 
      EF,    Linq2Sql ,  ,   .     ,   code first  .      ObjectMaterialized     (    )      .        DateTime ,       ComplexType ,        reference type. 
 
 RequiredAttribute 
           EF. 
 
 ,      Owner , Sender , Receiver  Thread   Required . -,      ,       NOT NULL ,  -,      EF. 
 
 , -,           ? 
 var message = context.Messages.Find(1); message.IsRead = true; context.SaveChanges(); 
   ,       -  .  DbEntityValidationException . 
 
  RequiredAttribute   ,        null,        .  , ,  . 
 
   :      (),    (),  try-catch  SaveChanges      catch (),  ,   (),      RequiredAttribute   NOT NULL  Fluent API. , ,   ,         ,     ,           (  Required   null      UPDATE ).   ,         ,    . 
 
  (tl;dr) 
    EF  -       ?  .    ,  Microsoft      -            EF. 
 
   ,      EF      ,     ,     .    ,        ,             ,          EF. 
 
     EF    Linq2Sql? ,  , .          code first (    ),          .     ,     (   EF6 ).           -- (     ,         )  ..  ORM-    EF –  . 
 
     ,      ,    - Entity Framework.        // ,    .    . 

   IQueryable    ,  ,     ,   Linq2Entities,     .    (--)    . ,      extension methods  IQueryable   ,    . 
 
    Find   . Find      ,             .  ,    context.Messages.Find(1)   ,         .      . ,          . 
 context.Accounts.Load(); //     -    var m = context.Messages.First(); Console.WriteLine(m.Owner.Name); 
 SQL SELECT [Extent1].[Id] AS [Id], [Extent1].[Name] AS [Name] FROM [dbo].[Account] AS [Extent1] GO SELECT TOP (1) [c].[Id] AS [Id], [c].[IsRead] AS [IsRead], [c].[Date] AS [Date], [c].[Text] AS [Text], [c].[Thread_Id] AS [Thread_Id], [c].[Owner_Id] AS [Owner_Id], [c].[Sender_Id] AS [Sender_Id], [c].[Receiver_Id] AS [Receiver_Id] FROM [dbo].[Message] AS [c] 
   context.Messages.Include(f=>f.Owner).First()         . :    Include    SQL-,   . 
 
  ,     ,     ,       ,       context.Set().Local,      ,   .   SaveChanges .         .     Linq2Sql. 
 
   :        1000   EF   2-3  ,  Linq2Sql. , API   ,    Linq2Sql . 
 
   
     .     Add          Added .    SubmitChanges  ,      INSERT     .   navigation property,       ,     Added     (      ). 
 
    : 
       ValidateOnSaveEnabled  AutoDetectChangesEnabled .    .         .        ,         GC    .  ,      100 . 
      StackOverflow . 
    EF  ,     ( ) Linq2Sql. , ,     Linq2Sql. 
 
     
       .NET ORM-.      Bulk-. ,   SQL     , ORM    . 
 ,        .  EF     : 
 var messages = context.Messages.Where(f=>f.Thread.Id == threadId); foreach (var m in messages) m.IsRead = true; context.SaveChanges(); 
 SQL SELECT [Extent1].[Id] AS [Id], [Extent1].[IsRead] AS [IsRead], [Extent1].[Date] AS [Date], [Extent1].[Text] AS [Text], [Extent1].[Thread_Id] AS [Thread_Id], [Extent1].[Owner_Id] AS [Owner_Id], [Extent1].[Sender_Id] AS [Sender_Id], [Extent1].[Reciever_Id] AS [Reciever_Id] FROM [dbo].[Message] AS [Extent1] WHERE [Extent1].[Thread_Id] = @p__linq__0 update [dbo].[Message] set [IsRead] = @0 where ([Id] = @1) --(N ) 
 -,        ,         .   , ,   ,     –  .  ,     ,    .           . 
 
    update/delete   .    ,        . 
 
  EntityFramework.Extended       : 
 var messages = context.Messages.Where(f=>f.Thread.Id == threadId); messages.Update(f => new Message {IsRead = true}); 
 SQL UPDATE [dbo].[Message] SET [IsRead] = @p__update__0 FROM [dbo].[Message] AS j0 INNER JOIN ( SELECT [Extent1].[Id] AS [Id] FROM [dbo].[Message] AS [Extent1] WHERE [Extent1].[Thread_Id] = @p__linq__0 ) AS j1 ON (j0.[Id] = j1.[Id]) 
        .  ,    SaveChanges – SQL     .       ,       - ,     /. 
 
  ,      ,      dynamic         ( , ,  IntelliTrace),        .     (EntityFramework  ). 
   10 ,   10000 ,  EntityFramework 8 935 EntityFramework.Extended 28 83 
   ,  EntityFramework.Extended     ,      .    . 
 
   navigation property 
     –           . « !»       : 
 var count = folder.Threads.Count(); 
   ,   navigation properties,  ,     SQL. 
 SQL SELECT [Extent2].[Id] AS [Id], [Extent2].[Subject] AS [Subject] FROM [dbo].[ThreadsInFolders] AS [Extent1] INNER JOIN [dbo].[MessageThread] AS [Extent2] ON [Extent1].[MessageThread_Id] = [Extent2].[Id] WHERE [Extent1].[MessageFolder_Id] = @EntityKeyValue1 
   EF,   Linq2Sql,  Count() , Any() ,       ,   navigation property,        .   ,    «»  .  ,     ,  : 
 var count = context.Threads.Count(f => f.Folders.Any(e => e.Id == folder.Id))); 
 SQL SELECT [GroupBy1].[A1] AS [C1] FROM ( SELECT COUNT(1) AS [A1] FROM [dbo].[MessageThread] AS [Extent1] WHERE EXISTS (SELECT 1 AS [C1] FROM [dbo].[ThreadsInFolders] AS [Extent2] WHERE ([Extent1].[Id] = [Extent2].[MessageThread_Id]) AND ([Extent2].[MessageFolder_Id] = @p__linq__0) ) ) AS [GroupBy1] 
   ,      ,    , ,     ,  «  ». 
 
  
          –        ,   . 
 
     : 
 Response.Cache.SetLastModified(lastUpdated); 
  lastUpdated –    ,    . 
    ,  ASP.NET MVC       ToUniversalTime() ,     : 
 if (utcDate > DateTime.UtcNow) { throw new ArgumentOutOfRangeException("utcDate"); } 
     –    , DateTime    Kind        DateTimeKind.Undefined ( ,      ,      -  UTC   ).       ,   ,       (     DateTimeKind ),    ToUniversalTime()  ToLocalTime()         . ,         GMT - N. 
 
      EF,    Linq2Sql ,  ,   .     ,   code first  .      ObjectMaterialized     (    )      .        DateTime ,       ComplexType ,        reference type. 
 
 RequiredAttribute 
           EF. 
 
 ,      Owner , Sender , Receiver  Thread   Required . -,      ,       NOT NULL ,  -,      EF. 
 
 , -,           ? 
 var message = context.Messages.Find(1); message.IsRead = true; context.SaveChanges(); 
   ,       -  .  DbEntityValidationException . 
 
  RequiredAttribute   ,        null,        .  , ,  . 
 
   :      (),    (),  try-catch  SaveChanges      catch (),  ,   (),      RequiredAttribute   NOT NULL  Fluent API. , ,   ,         ,     ,           (  Required   null      UPDATE ).   ,         ,    . 
 
  (tl;dr) 
    EF  -       ?  .    ,  Microsoft      -            EF. 
 
   ,      EF      ,     ,     .    ,        ,             ,          EF. 
 
     EF    Linq2Sql? ,  , .          code first (    ),          .     ,     (   EF6 ).           -- (     ,         )  ..  ORM-    EF –  . 
 
     ,      ,    - Entity Framework.        // ,    .    .