如果快照事务隔离避免在客户端ADO.NET应用程序？那么，什么是它的主要目的是什么？ [英] Should snapshot transaction isolation be avoided in client ADO.NET applications? then, what was its main purpose?

问题描述

在读[1]：

• 在持久数据库连接的要求限制快照隔离的可扩展性，因此不应该被用作实现乐观并发的通用方法

我想明白了：
什么是ADO.NET持续连接？
我根本不记得，在编程.NET应用程序，我配置SQL Server连接的任何持久性。
在哪里？

I'd like to understand:
What is persistent connection in ADO.NET?
I simply do not remember that, while programming .NET apps, I configured any persistence of SQL Server connections.
Where was it?

时的连接模式持续连接的反义词？

Is "persistent connection" antonym of disconnected mode?

什么是需要影响到在编码ADO.NET客户端的应用程序永久连接（在，恩，C＃）？
如何快照事务隔离在ADO.NET客户端应用程序中使用？
什么是参与的（快照事务隔离级别）的主要目标区域？

What are implications of the need to have persistent connection in coding ADO.NET client apps (in, for ex., C#)?
How snapshot transaction isolation is to be used in ADO.NET client apps?
What is its (snapshot transaction isolation levels) main target area of engagement?

另外，我有些糊涂，看了大多数.NET框架和功能，如，为前，LINQ2SQL，不支持保守式锁定（当然，提示）......但分布式事务不支持快照隔离[ 2]

Also, I am somewhat confused, having read that most .NET frameworks and features, like, for ex., Linq2SQL, do not support pessimistic locking (well, hints)... but distributed transactions do not support snapshot isolation [2]

如果SQL Server内置的乐观并发功能来避免和定制乐观（版本）事务支持取代？
再次，什么是对和他们为什么在这样的介绍（很难理解对我来说）执行？

Should SQL Server built-in optimistic concurrency functionalities be avoided and substituted by custom optimistic (versioning) transaction support?
Again, what's for and why were they introduced in such (difficult to understand for me) implementation?

[1]丹·古斯曼的博客。
并发型号混乱II
的http://weblogs.sqlteam.com/dang/archive/2008/06/07/Concurrency-Model-Confusion-II.aspx
[2]
为什么没有快照隔离在SQL Server的
分布式事务支持 <一href="http://stackoverflow.com/questions/1331734/why-isnt-snapshot-isolation-supported-with-distributed-transactions-in-sql-serve">Why是不是快照隔离在SQL Server的
分布式事务支持 [3]
当美元的事务隔离p $ PFER悲观模型过于乐观呢？
<一href="http://stackoverflow.com/questions/4088430/when-to-$p$pfer-pessimistic-model-of-transaction-isolation-over-optimistic-one">when以事务隔离了乐观的preFER悲观模式呢？

[1] Dan Guzman's Blog.
Concurrency Model Confusion II
http://weblogs.sqlteam.com/dang/archive/2008/06/07/Concurrency-Model-Confusion-II.aspx
[2]
Why isn't Snapshot isolation supported with Distributed Transactions in SQL Server
Why isn't Snapshot isolation supported with Distributed Transactions in SQL Server
[3]
when to prefer pessimistic model of transaction isolation over optimistic one?
when to prefer pessimistic model of transaction isolation over optimistic one?

推荐答案

虽然文档不是很清楚，我，这里是我如何跨preT它。如果我在我专用的连接，我可以使用快照隔离来实现乐观并发，因为我在这篇文章中描述：<一href="http://www.simple-talk.com/sql/t-sql-programming/developing-modifications-that-survive-concurrency/"相对=nofollow的生存并发>开发修改。如果有冲突，你会得到一个错误信息：快照隔离事务中止由于更新冲突

Although the documentation is not quite clear to me, here is how I interpret it. If I have a connection in my exclusive use, I can use snapshot isolation to implement optimistic concurrency, as I described in this article: Developing Modifications that Survive Concurrency. If there is a conflict, you will get an error message: "Snapshot isolation transaction aborted due to update conflict."

然而，利用这种方法，我们必须保持连接打开，我们不能使用连接池。请注意，在某些环境中空闲连接部分闲置一段时间后自动死亡。

However, to utilize this approach, we must keep the connection open, and we cannot use connection pooling. Note that in some environments idle connections are automatically killed after some idle period.

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