我在某些部署的系统上遇到了SQL Server Compact 4.0 SP1 x64的奇怪问题。问题表现为连接打开到SQL CE数据库非常慢。大多数情况下，这种延迟似乎大约是15秒，但它可能会更长（如下面的日志中所示）。打开连接后，后续访问似乎很快如果尝试快速连续发生。但是，只要有一段时间没有访问尝试，就会再次出现缓慢的情况。
这些系统都运行SQL Server 2008 R2，并且都是x64。但是，并非所有已部署的系统都会出现此问题。我的观察是未修补的系统（没有最新的Windows更新）更有可能遇到这个问题。
请参阅以下代码示例以及运行示例时生成的日志。第一个日志显示未修补系统上的运行，第二个日志显示应用了所有Windows更新的计算机上的运行。
代码示例
var watch = new System.Diagnostics.Stopwatch();
_logger.Info("Persistent cache initialization starting...");
watch.Start();
using (var context = new CachedResponseContext())
{
context.Database.Log = _logger.Debug;
context.Database.Initialize(force: false);
}
watch.Stop();
_logger.InfoFormat("Persistent cache initialization completed in {0} milliseconds.", watch.ElapsedMilliseconds);
日志显示SLOW连接已打开
请注意第一个日志语句和第二个日志语句之间的大量时间（~78秒）......
2015-03-24 08:49:43,749 [ 4] DEBUG | Redacted.Caching.DatabaseCache | Persistent cache initialization starting...
2015-03-24 08:51:01,899 [ 4] DEBUG | Redacted.Caching.DatabaseCache | Opened connection at 3/24/2015 8:51:01 AM -07:00
2015-03-24 08:51:01,903 [ 4] DEBUG | Redacted.Caching.DatabaseCache |
SELECT Count(*)
FROM INFORMATION_SCHEMA.TABLES AS t
WHERE t.TABLE_NAME IN ('CachedResponses','edmMetadataContextTableName')
2015-03-24 08:51:01,903 [ 4] DEBUG | Redacted.Caching.DatabaseCache |
2015-03-24 08:51:01,905 [ 4] DEBUG | Redacted.Caching.DatabaseCache | -- Executing at 3/24/2015 8:51:01 AM -07:00
2015-03-24 08:51:01,940 [ 4] DEBUG | Redacted.Caching.DatabaseCache | -- Completed in 33 ms with result: 1
2015-03-24 08:51:01,940 [ 4] DEBUG | Redacted.Caching.DatabaseCache |
2015-03-24 08:51:01,947 [ 4] DEBUG | Redacted.Caching.DatabaseCache | Closed connection at 3/24/2015 8:51:01 AM -07:00
2015-03-24 08:51:02,104 [ 4] DEBUG | Redacted.Caching.DatabaseCache | Opened connection at 3/24/2015 8:51:02 AM -07:00
2015-03-24 08:51:03,196 [ 4] DEBUG | Redacted.Caching.DatabaseCache | SELECT
[GroupBy1].[A1] AS [C1]
FROM ( SELECT
COUNT(1) AS [A1]
FROM [__MigrationHistory] AS [Extent1]
WHERE [Extent1].[ContextKey] = @p__linq__0
) AS [GroupBy1]
2015-03-24 08:51:03,196 [ 4] DEBUG | Redacted.Caching.DatabaseCache |
2015-03-24 08:51:03,197 [ 4] DEBUG | Redacted.Caching.DatabaseCache | -- p__linq__0: 'Redacted.Caching.CachedResponseContext' (Type = String)
2015-03-24 08:51:03,197 [ 4] DEBUG | Redacted.Caching.DatabaseCache | -- Executing at 3/24/2015 8:51:03 AM -07:00
2015-03-24 08:51:03,212 [ 4] DEBUG | Redacted.Caching.DatabaseCache | -- Completed in 14 ms with result: SqlCeDataReader
2015-03-24 08:51:03,212 [ 4] DEBUG | Redacted.Caching.DatabaseCache |
2015-03-24 08:51:03,230 [ 4] DEBUG | Redacted.Caching.DatabaseCache | Closed connection at 3/24/2015 8:51:03 AM -07:00
2015-03-24 08:51:03,245 [ 4] DEBUG | Redacted.Caching.DatabaseCache | Opened connection at 3/24/2015 8:51:03 AM -07:00
2015-03-24 08:51:03,313 [ 4] DEBUG | Redacted.Caching.DatabaseCache | SELECT TOP (1)
[Project1].[C1] AS [C1],
[Project1].[MigrationId] AS [MigrationId],
[Project1].[Model] AS [Model],
[Project1].[ProductVersion] AS [ProductVersion]
FROM ( SELECT
[Extent1].[MigrationId] AS [MigrationId],
[Extent1].[Model] AS [Model],
[Extent1].[ProductVersion] AS [ProductVersion],
1 AS [C1]
FROM [__MigrationHistory] AS [Extent1]
WHERE [Extent1].[ContextKey] = @p__linq__0
) AS [Project1]
ORDER BY [Project1].[MigrationId] DESC
2015-03-24 08:51:03,313 [ 4] DEBUG | Redacted.Caching.DatabaseCache |
2015-03-24 08:51:03,314 [ 4] DEBUG | Redacted.Caching.DatabaseCache | -- p__linq__0: 'Redacted.Caching.CachedResponseContext' (Type = String)
2015-03-24 08:51:03,314 [ 4] DEBUG | Redacted.Caching.DatabaseCache | -- Executing at 3/24/2015 8:51:03 AM -07:00
2015-03-24 08:51:03,315 [ 4] DEBUG | Redacted.Caching.DatabaseCache | -- Completed in 1 ms with result: SqlCeDataReader
2015-03-24 08:51:03,315 [ 4] DEBUG | Redacted.Caching.DatabaseCache |
2015-03-24 08:51:03,332 [ 4] DEBUG | Redacted.Caching.DatabaseCache | Closed connection at 3/24/2015 8:51:03 AM -07:00
2015-03-24 08:51:03,355 [ 4] DEBUG | Redacted.Caching.DatabaseCache | Persistent cache initialization completed in 79601 milliseconds.
日志显示FAST连接已打开
请注意第一个日志语句与第二个日志之间的少量时间......
2015-03-24 08:34:03,529 [ 4] DEBUG | Redacted.Caching.DatabaseCache | Persistent cache initialization starting...
2015-03-24 08:34:04,471 [ 4] DEBUG | Redacted.Caching.DatabaseCache | Opened connection at 3/24/2015 8:34:04 AM -07:00
2015-03-24 08:34:04,475 [ 4] DEBUG | Redacted.Caching.DatabaseCache |
SELECT Count(*)
FROM INFORMATION_SCHEMA.TABLES AS t
WHERE t.TABLE_NAME IN ('CachedItems','edmMetadataContextTableName')
2015-03-24 08:34:04,475 [ 4] DEBUG | Redacted.Caching.DatabaseCache |
2015-03-24 08:34:04,477 [ 4] DEBUG | Redacted.Caching.DatabaseCache | -- Executing at 3/24/2015 8:34:04 AM -07:00
2015-03-24 08:34:04,513 [ 4] DEBUG | Redacted.Caching.DatabaseCache | -- Completed in 33 ms with result: 1
2015-03-24 08:34:04,513 [ 4] DEBUG | Redacted.Caching.DatabaseCache |
2015-03-24 08:34:04,517 [ 4] DEBUG | Redacted.Caching.DatabaseCache | Closed connection at 3/24/2015 8:34:04 AM -07:00
2015-03-24 08:34:04,662 [ 4] DEBUG | Redacted.Caching.DatabaseCache | Opened connection at 3/24/2015 8:34:04 AM -07:00
2015-03-24 08:34:05,725 [ 4] DEBUG | Redacted.Caching.DatabaseCache | SELECT
[GroupBy1].[A1] AS [C1]
FROM ( SELECT
COUNT(1) AS [A1]
FROM [__MigrationHistory] AS [Extent1]
WHERE [Extent1].[ContextKey] = @p__linq__0
) AS [GroupBy1]
2015-03-24 08:34:05,726 [ 4] DEBUG | Redacted.Caching.DatabaseCache |
2015-03-24 08:34:05,727 [ 4] DEBUG | Redacted.Caching.DatabaseCache | -- p__linq__0: 'Redacted.Caching.CachedResponseContext' (Type = String)
2015-03-24 08:34:05,727 [ 4] DEBUG | Redacted.Caching.DatabaseCache | -- Executing at 3/24/2015 8:34:05 AM -07:00
2015-03-24 08:34:05,743 [ 4] DEBUG | Redacted.Caching.DatabaseCache | -- Completed in 15 ms with result: SqlCeDataReader
2015-03-24 08:34:05,743 [ 4] DEBUG | Redacted.Caching.DatabaseCache |
2015-03-24 08:34:05,754 [ 4] DEBUG | Redacted.Caching.DatabaseCache | Closed connection at 3/24/2015 8:34:05 AM -07:00
2015-03-24 08:34:05,770 [ 4] DEBUG | Redacted.Caching.DatabaseCache | Opened connection at 3/24/2015 8:34:05 AM -07:00
2015-03-24 08:34:05,842 [ 4] DEBUG | Redacted.Caching.DatabaseCache | SELECT TOP (1)
[Project1].[C1] AS [C1],
[Project1].[MigrationId] AS [MigrationId],
[Project1].[Model] AS [Model],
[Project1].[ProductVersion] AS [ProductVersion]
FROM ( SELECT
[Extent1].[MigrationId] AS [MigrationId],
[Extent1].[Model] AS [Model],
[Extent1].[ProductVersion] AS [ProductVersion],
1 AS [C1]
FROM [__MigrationHistory] AS [Extent1]
WHERE [Extent1].[ContextKey] = @p__linq__0
) AS [Project1]
ORDER BY [Project1].[MigrationId] DESC
2015-03-24 08:34:05,842 [ 4] DEBUG | Redacted.Caching.DatabaseCache |
2015-03-24 08:34:05,842 [ 4] DEBUG | Redacted.Caching.DatabaseCache | -- p__linq__0: 'Redacted.Caching.CachedResponseContext' (Type = String)
2015-03-24 08:34:05,842 [ 4] DEBUG | Redacted.Caching.DatabaseCache | -- Executing at 3/24/2015 8:34:05 AM -07:00
2015-03-24 08:34:05,844 [ 4] DEBUG | Redacted.Caching.DatabaseCache | -- Completed in 1 ms with result: SqlCeDataReader
2015-03-24 08:34:05,844 [ 4] DEBUG | Redacted.Caching.DatabaseCache |
2015-03-24 08:34:05,851 [ 4] DEBUG | Redacted.Caching.DatabaseCache | Closed connection at 3/24/2015 8:34:05 AM -07:00
2015-03-24 08:34:05,875 [ 4] DEBUG | Redacted.Caching.DatabaseCache | Persistent (database) response cache initialization completed in 2345 milliseconds.
我非常感谢任何建议。当然，我计划强烈建议所有系统都应用最新的Windows更新。但是，我非常想知道问题可能是什么以及哪些特定的Windows更新可能是有效的。
非常感谢，
答案 0 :(得分：0)
很可能是由于代理配置无效，但也有其他原因http://erikej.blogspot.dk/2013/08/faq-why-is-opening-my-sql-server.html
此外，在使用EF而不是原始ADO.NET或直接表访问时，您通常会遇到一定的开销