ObjectContext.Connection.BeginTransaction() 是否使用 MSDTC？

发布于 2024-11-26 13:07:28 字数 123 浏览 1 评论 0原文

我想确认实体框架的ObjectContext.Connection.BeginTransaction()方法返回的事务是否使用MSDTC（微软分布式事务协调器）的支持？

有没有办法在不支持MSDTC的情况下使用事务？

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装迷糊 2024-12-03 13:07:28

在一定条件下，它会自动升级为由 MSDTC 协调的交易。每次调用 ObjectContext.SaveChanges() 时，如果范围内尚无事务，则会创建一个新事务（如果范围内已存在活动事务，则它将登记在该事务中）。但是，默认情况下，每次调用 ObjectContext.SaveChanges() 时，连接也会打开和关闭。因此，如果您在方法开头调用 ObjectContext.Connection.BeginTransaction()，然后在保留原始事务的同时多次调用 ObjectContext.SaveChanges()，对于某些版本的 SQL Server 和实体框架，这可能会导致事务升级为 MSDTC，因为它现在在单个事务中使用不同的连接。如果您想避免事务升级为 MSDTC，请在开始时显式打开连接并在完成后关闭它：

using(MyEntities context = new MyEntities())
using(DbConnection conn = context.Connection)
{
    conn.Open();
    DbTransaction transaction = conn.BeginTransaction();

    // now do stuff within the transaction scope

    transaction.Commit();
}

但是，建议您使用 TransactionScope，因为它更灵活，对平台的依赖性较小，如果将来您决定确实需要需要 MSDTC 的东西，这将使您更轻松。如果存在活动的 TransactionScope，EntityFramework 将自动加入事务：

using(TransactionScope transaction = new TransactionScope())
using(MyEntities context = new MyEntities())
using(DbConnection conn = context.Connection)
{
    conn.Open();

    // now do stuff within the transaction scope

    transaction.Complete();
}

It will automatically promote to a transaction coordinated by MSDTC under certain conditions. Each time you call ObjectContext.SaveChanges() a new transaction is created if there isn't already one in scope (if there is already an active transaction in scope, it will enlist in that transaction). However, by default, the connection will also be opened and closed each time you call ObjectContext.SaveChanges(). So if you're calling ObjectContext.Connection.BeginTransaction() at the beginning of a method, then calling ObjectContext.SaveChanges() multiple times while holding onto the original transaction, with some versions of SQL Server and Entity Framework, this can cause the transaction to get promoted to MSDTC because it's now using different connections within a single transaction. If you're trying to avoid your transaction getting promoted to MSDTC, then explicitly open your connection at the beginning and close it when you're done:

using(MyEntities context = new MyEntities())
using(DbConnection conn = context.Connection)
{
    conn.Open();
    DbTransaction transaction = conn.BeginTransaction();

    // now do stuff within the transaction scope

    transaction.Commit();
}

However, it's recommended that you use a TransactionScope, as it's more flexible, less platform-dependent, and will make it easier on you if in the future you decide you do actually need to something that requires MSDTC. EntityFramework will automatically enlist in the transaction if there's an active TransactionScope:

using(TransactionScope transaction = new TransactionScope())
using(MyEntities context = new MyEntities())
using(DbConnection conn = context.Connection)
{
    conn.Open();

    // now do stuff within the transaction scope

    transaction.Complete();
}

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