Optimistic concurrency: IsConcurrencyToken and RowVersion
c# concurrency ef-code-first entity-framework sql-server
Question
I'm establishing the standard concurrency strategy I'll employ in my application.
I choose to adopt a positive approach.
My entire database is mapped asTable per Type (TPT)
(Using ancestry). I immediately discovered that utilizing columns of type RowVersion with inheritance on Entity Framework has a problem:
Product
Id INT IDENTITY PRIMARY KEY
RowVersion ROWVERSION
Car (inherits Product records)
Color TYNIINT NOT NULL,
AnotherProperty....  Â
Whenever I alter a record of theCar
the RowVersion column from tableProduct
table won't be changed.
I'm going to use a type column.datetime2 (7)
in Product
and manually update it if any records in the tables that inherit from it are changed.
I feel like I'm remaking the wheel.
Is the optimistic concurrency strategy also applicable toROWVERSION
the use ofTable per Type (TPT)
Entity Framework, please?
Edit
I mapped:
class Product
{
int Id { get; set; }
string Name { get; set; }
byte[] RowVersion { get; set; }
}
class Car : Product
{
int Color { get; set; }
}
conventions for CodeFirst.
The RowVersion property is the onlyProduct
entity's definitions are unique:
modelBuilder.Entity<Product>()
.Property(t => t.RowVersion)
.IsConcurrencyToken();
Accepted Answer
When dealing with SQL Server, you must use this mapping in both EF6 and EF-core:
modelBuilder.Entity<Product>()
.Property(t => t.RowVersion)
.IsRowVersion(); // Not: IsConcurrencyToken
A property is configured as a concurrency token by IsConcurrencyToken, however (when used for abyte[]
property)
- the type of data is
varbinary(max) - its worth remains constant
nullIn the absence of initialization - If a record is modified, its value is not automatically incremented.
On the other side, IsRowVersion
- possess datatype
rowversioneither in SQL Servertimestampin previous iterations), so - it never has a null value, and
- When a record is updated, its value is constantly automatically incremented.
- Likewise, an optimistic concurrency token is automatically configured for the property.
At this point, updating aCar
Two update statements are displayed:
DECLARE @p int
UPDATE [dbo].[Product]
SET @p = 0
WHERE (([Id] = @0) AND ([Rowversion] = @1))
SELECT [Rowversion]
FROM [dbo].[Product]
WHERE @@ROWCOUNT > 0 AND [Id] = @0
UPDATE [dbo].[Car]
SET ...
The first statement increments the rowversion rather than updating anything, and it will raise a concurrency exception if the rowversion was modified in between.
The [System.ComponentModel.DataAnnotations.Schema.Timestamp]
attribute is comparable to in data annotations.IsRowVersion()
:
[Timestamp]
public byte[] RowVersion { get; set; }
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