空闲一段时间后，如何防止LocalDB分离MDF文件? [英] How to prevent LocalDB from detaching MDF file after some idle time?

问题描述

我正在构建一个.NET 4.5(winforms)应用程序，该应用程序使用LocalDB通过以下连接字符串来处理本地MDF文件:

I'm building a .NET 4.5 (winforms) application that uses LocalDB to work with a local MDF file, using this connection string:

Data Source=(LocalDB)\v11.0;AttachDbFilename=|DataDirectory|\DB\DatabaseFile.mdf;Integrated Security=True;MultipleActiveResultSets=True

当我运行我的应用程序时，第一个SQL查询需要一些时间来执行-没什么大不了的，大约需要2到3秒钟.之后，所有下一个SQL查询将立即执行.我假设在第一次执行过程中需要额外的几秒钟才能将MDF文件附加到本地SQL Server服务.对吧?

When I run my application, the first SQL query takes some time to execute - nothing drastic, about 2 or 3 seconds. After that, all next SQL queries are executed instantly. I assume that the extra seconds during the first execution are needed to attach the MDF file to a local SQL Server service. Right?

但是，我注意到，如果自上一次执行SQL查询以来经过了10分钟(或大约10分钟)，则下一个SQL查询将再次花费那2-3秒的时间来执行.我假设经过一段空闲时间后，MDF会分离，并且在调用新的SQL命令时，它将再次重新附加它.

I noticed, however, that if 10 minutes (or so) pass since an SQL query was last performed, the next SQL query will again take those 2-3 seconds more to execute. I assume that after some idle time, the MDF gets detached, and when the new SQL command is called, it re-attaches it once again.

我想知道，是否有一种方法可以覆盖此行为?

I'm wondering, is there a way to override this behavior?

我知道我可以创建一个Timer，每隔几分钟执行一次简单的查询，但是有没有更好，更干净的解决方案?

I know I could create a Timer, that performs a simple query every few minutes, but is there a better, cleaner solution?

推荐答案

我更怀疑您的数据/索引不再在内存中.

I would more suspect that your data / index is no longer in memory.

您可以运行一个非常快速的查询，例如选择"a"，以了解是否是连接时间.

You could run a very fast query like select 'a' to know if it was the connect time.

关于强制您的表/索引保留在内存中.
我非常建议您让.NET和SQL进行自己的内存管理.

As for forcing your table / index to stay in memory.
I would so much advise you to let .NET and SQL do their own memory management.

2-3秒不是很多.
查看查询计划-也许您可以使其更快(甚至不在内存中).

2-3 seconds is not much.
Look at the query plan - maybe you can make it faster (even not in memory).

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