如果值不相符,EF Core 就會假設另一位使用者已執行衝突作業,而將目前的交易中止,並擲回 DbUpdateConcurrencyException。當另一位使用者或流程正在執行與目前作業衝突的作業時,稱為並行衝突。在關聯式資料庫上,EF Core 會檢查 UPDATE 和DELETE 陳述式 WHERE 子句中並行權杖的值,以偵測並行衝突。必須...
最常用的 Token 是设置一个 version 版本号,每更新完就 version+1。还可以选用 TimeStamp。但是更好的选择是,选取已有列中的某一列设置为 Token。 优点:响应速度快 并发高 缺点:如果冲突频率大,乐观锁要作废重试多次,代价较高 EF Core 中的并发冲突 EF Core 采用的是乐观并发控制。 EF Core 实现 乐观并发控...
在EFCore,可以借用属性的 IsRowVersion 配置,如果一个属性被配置为 RowVersion,那么 EFCore 会自动将它设置为并发令牌,并且在对应的数据库分配特殊的时间戳类型给它(在 SQLServer,该类型是 rowversion 或 timestamp),每次插入或更新该行数据时,EFCore 会自动为 RowVersion 列生成一个新的值。 以SQLServer 为例,...
.IsOption()//null.IsRequired()//not null.HasMaxLength(50) .HasMaxLength(50).IsFixedLength()//change type from nvarchar to nchar.HasPrecision(2,2)//set size decimal(2,2).IsCurrencyToken()//concurrency check.IsRowVersion()//timestamp type byte[] make it as concurrency column; } } 级...
dotnetcore EF 乐观锁并发控制 使用IsConcurrencyToken()设置并发token builder.Property(h => h.Owner).IsConcurrencyToken(); 使用SQL语句类似以下 updatehousesetowner=@p0whereid=1andowner=@p1-- 通过引用旧的owner值来更新,如果owner值已改变,则更新失败,发出DbUpdateConcurrencyException。
The value used for the concurrency token is typically, but does not have to be, the original value of the concurrency token property. Return the number of rows affected so that EF Core can compare this against the expected number of rows affected and throw a DbUpdateConcurrencyException if ...
In EF Core, optimistic concurrency is implemented by configuring a property as aconcurrency token. The concurrency token is loaded and tracked when an entity is queried - just like any other property. Then, when an update or delete operation is performed duringSaveChanges(), the value of the ...
Concurrency Token (ConcurrencyCheck)You can use the IsConcurrencyToken() method to configure a property as a concurrency token.class MyContext : DbContext { public DbSet<Person> People { get; set; } protected override void OnModelCreating(ModelBuilder modelBuilder) { modelBuilder.Entity<Person>() ...
In EF Core, optimistic concurrency is implemented by configuring a property as a concurrency token. The concurrency token is loaded and tracked when an entity is queried - just like any other property. Then, when an update or delete operation is performed during SaveChanges(), the value of ...
During a transaction, EF Core reads the new timestamp using UPDATE … + SELECT [timestamp]… However, the read timestamp is not used. If this is by design there should be at least a documentation telling the users that in transaction the t...