带有NOLOCK的实体框架

Question

如何NOLOCK在实体框架上使用该功能？XML是做到这一点的唯一方法吗？

Answer 1

否，但是您可以启动事务并将隔离级别设置为uncommited。这本质上与NOLOCK相同，但是它不是针对每个表执行此操作，而是针对事务范围内的所有操作执行此操作。

如果这听起来像您想要的，那么您可以按照以下方法进行操作...

//declare the transaction options

var transactionOptions = new System.Transactions.TransactionOptions();

//set it to read uncommited

transactionOptions.IsolationLevel = System.Transactions.IsolationLevel.ReadUncommitted;

//create the transaction scope, passing our options in

using (var transactionScope = new System.Transactions.TransactionScope(

    System.Transactions.TransactionScopeOption.Required, 

    transactionOptions)

)

//declare our context

using (var context = new MyEntityConnection())

{

    //any reads we do here will also read uncomitted data

    //...

    //...

    //don't forget to complete the transaction scope

    transactionScope.Complete();

}

Answer 2

扩展方法可以使此操作更容易

public static List<T> ToListReadUncommitted<T>(this IQueryable<T> query)

{

    using (var scope = new TransactionScope(

        TransactionScopeOption.Required, 

        new TransactionOptions() { 

            IsolationLevel = System.Transactions.IsolationLevel.ReadUncommitted }))

    {

        List<T> toReturn = query.ToList();

        scope.Complete();

        return toReturn;

    }

}

public static int CountReadUncommitted<T>(this IQueryable<T> query)

{

    using (var scope = new TransactionScope(

        TransactionScopeOption.Required, 

        new TransactionOptions() { 

            IsolationLevel = System.Transactions.IsolationLevel.ReadUncommitted }))

    {

        int toReturn = query.Count();

        scope.Complete();

        return toReturn;

    }

}