jit*_*bit 27 sql-server sql-server-2016
将 SQL Server 2014 升级到 2016 后，服务器每隔几个小时就会不断重置缓存的执行计划和dm*视图（如dm_exec_query_stats）等
至于如果有人执行DBCC FREEPROCCACHE和DBCC DROPCLEANBUFFERS手动（除了没人做，它会自动发生）。
同一个数据库在 SQL Server 2014 和 Windows Server 2012 上运行良好，但在迁移到 SQL Server 2016（和 Windows Server 2016）后事情就变糟了
事情我检查：数据库并没有具备“自动关闭”标志。SQL 服务器ad hoc optimized设置为true（我认为它会有所帮助，但它没有）。“查询存储”为“关闭”。服务器有 16 GB 内存。
“SQL Server 日志”中也没有任何帮助。只是每周备份消息...
我还检查了这篇文章https://docs.microsoft.com/en-us/sql/t-sql/statements/alter-database-transact-sql-set-options（向下滚动到“示例”部分，就在上面它）有自动清除计划的情况列表。这些都不适用。
不幸的是，这些建议都没有帮助。授予 LPIM 权限，检测和修复为同一查询生成大量计划的非参数化查询，降低“最大服务器内存”......计划不断随机重置，从每几个小时到每 5-10 分钟。如果服务器“处于内存压力之下”，为什么 2014 版本在同一台机器上运行良好。
这是请求的 sp_Blitz 输出
**Priority 10: Performance**:
- Query Store Disabled - The new SQL Server 2016 Query Store feature has not been enabled on this database.
* xxx
**Priority 50: Server Info**:
- Instant File Initialization Not Enabled - Consider enabling IFI for faster restores and data file growths.
**Priority 100: Performance**:
- Resource Governor Enabled - Resource Governor is enabled. Queries may be throttled. Make sure you understand how the Classifier Function is configured.
**Priority 120: Query Plans**:
- Implicit Conversion Affecting Cardinality - One of the top resource-intensive queries has an implicit conversion that is affecting cardinality estimation.
*
- Missing Index - One of the top resource-intensive queries may be dramatically improved by adding an index.
*
- RID or Key Lookups - One of the top resource-intensive queries contains RID or Key Lookups. Try to avoid them by creating covering indexes.
*
**Priority 170: File Configuration**:
- System Database on C Drive
* master - The master database has a file on the C drive. Putting system databases on the C drive runs the risk of crashing the server when it runs out of space.
* model - The model database has a file on the C drive. Putting system databases on the C drive runs the risk of crashing the server when it runs out of space.
* msdb - The msdb database has a file on the C drive. Putting system databases on the C drive runs the risk of crashing the server when it runs out of space.
**Priority 200: Backup**:
- MSDB Backup History Not Purged msdb - Database backup history retained back to Jun 10 2017 9:47PM
**Priority 200: Informational**:
- Backup Compression Default Off - Uncompressed full backups have happened recently, and backup compression is not turned on at the server level. Backup compression is included with SQL Server 2008R2 & newer, even in Standard Edition. We recommend turning backup compression on by default so that ad-hoc backups will get compressed.
**Priority 200: Non-Default Server Config**:
- Agent XPs - This sp_configure option has been changed. Its default value is 0 and it has been set to 1.
- max server memory (MB) - This sp_configure option has been changed. Its default value is 2147483647 and it has been set to 15000.
- optimize for ad hoc workloads - This sp_configure option has been changed. Its default value is 0 and it has been set to 1.
- show advanced options - This sp_configure option has been changed. Its default value is 0 and it has been set to 1.
- xp_cmdshell - This sp_configure option has been changed. Its default value is 0 and it has been set to 1.
**Priority 200: Performance**:
- Buffer Pool Extensions Enabled - You have Buffer Pool Extensions enabled, and one lives here: Z:\sql_buffer_pool.BPE. It's currently 60.00000000000 GB. Did you know that BPEs only provide single threaded access 8KB (one page) at a time?
- cost threshold for parallelism - Set to 5, its default value. Changing this sp_configure setting may reduce CXPACKET waits.
**Priority 240: Wait Stats**:
- No Significant Waits Detected - This server might be just sitting around idle, or someone may have cleared wait stats recently.
**Priority 250: Informational**:
- SQL Server Agent is running under an NT Service account - I'm running as NT Service\SQLSERVERAGENT. I wish I had an Active Directory service account instead.
- SQL Server is running under an NT Service account - I'm running as NT Service\MSSQLSERVER. I wish I had an Active Directory service account instead.
**Priority 250: Server Info**:
- Default Trace Contents - The default trace holds 125 hours of data between Aug 19 2017 11:55AM and Aug 24 2017 4:59PM. The default trace files are located in: C:\Program Files\Microsoft SQL Server\MSSQL13.MSSQLSERVER\MSSQL\Log
- Hardware - Logical processors: 2. Physical memory: 15GB.
- Hardware - NUMA Config - Node: 0 State: ONLINE Online schedulers: 2 Offline schedulers: 0 Processor Group: 0 Memory node: 0 Memory VAS Reserved GB: 29
- Locked Pages In Memory Enabled - You currently have 12.02534484863 GB of pages locked in memory.
- Memory Model Unconventional - Memory Model: LOCK_PAGES
- Server Last Restart - Aug 20 2017 12:32PM
- Server Name - xx
- Services
- Service: SQL Full-text Filter Daemon Launcher (MSSQLSERVER) runs under service account NT Service\MSSQLFDLauncher. Last startup time: not shown.. Startup type: Manual, currently Running.
- Service: SQL Server (MSSQLSERVER) runs under service account NT Service\MSSQLSERVER. Last startup time: Aug 20 2017 12:32PM. Startup type: Automatic, currently Running.
- Service: SQL Server Agent (MSSQLSERVER) runs under service account NT Service\SQLSERVERAGENT. Last startup time: not shown.. Startup type: Automatic, currently Running.
- SQL Server Last Restart - Aug 20 2017 12:33PM
- SQL Server Service - Version: 13.0.4446.0. Patch Level: SP1. Edition: Enterprise Edition (64-bit). AlwaysOn Enabled: 0. AlwaysOn Mgr Status: 2
- Virtual Server - Type: (HYPERVISOR)
- Windows Version - You're running a pretty modern version of Windows: Server 2012R2 era, version 6.3
**Priority 254: Rundate**:
- Captain's log: stardate something and something...
Bre*_*zar 32
首先，获取清除计划缓存的确切时间。这是最简单的方法 - 它应该几乎立即运行，并且不会阻止任何人：
SELECT TOP 1 creation_time
FROM sys.dm_exec_query_stats WITH (NOLOCK)
ORDER BY creation_time;
如果该日期/时间对您来说似乎比您预期的要早，那么只会清除部分计划缓存。例如，也许有人正在执行索引重建或更新统计信息工作，这将刷新受影响的特定对象的计划缓存 - 但其他对象仍会保留。当系统查询（如 DMV 查询）持续存在时，我经常看到这种情况，但用户数据库计划已清除。
如果该日期/时间以特定时间间隔更新，例如似乎每 2 小时更新一次，例如 6:00、8:00、10:00 等，那么可能有人正在运行导致计划缓存清除。一旦您知道确切的频率，您就可以：
sp_WhoIsActive在此期间记录到表（最简单的方法，但最不可能将其缩小到导致它的确切查询）如果每次运行查询时该日期/时间都不断变化，那么您的服务器可能处于内存压力之下。运行它以生成基本的健康检查信息，然后您可以将其复制/粘贴到您的 Stack 问题中，以便我们对其进行诊断：
sp_Blitz @OutputType = 'markdown', @CheckServerInfo = 1, @CheckUserDatabaseObjects = 1
（披露：我是 的作者之一sp_Blitz。）
使用您的 sp_Blitz 数据更新了 2017/08/25 - 感谢您运行 sp_Blitz 并将其添加到您的问题中，它确实有助于显示一些内容。您在具有 2 个内核和 16GB RAM 的 VM 上运行 SQL Server 2016 Enterprise Edition。首先，关于许可的快速说明：如果您是通过来宾许可，最低购买要求是 4 个内核，而不是 2 个。（有关更多详细信息，请参阅SQL Server 许可指南。）4 个企业版内核约为 28,000 美元，而且看到在 16GB RAM 上花费如此多的许可资金是相当不寻常的。但是，如果您在主机级别授权 SQL Server Enterprise Edition，则可以忽略它并运行较小的 VM。
看起来您的 SQL Server 正面临外部内存压力。您有 16GB 的 RAM，并将最大服务器内存设置为 15GB。不幸的是，剩余的 1GB 空间不足以供操作系统使用（加上您将在那里运行的任何其他内容，例如备份软件和 SSMS。）在我们的 SQL Server 设置指南中，我们建议保留 4GB 或 10% 的免费空间，以哪个为准更大 - 在您的情况下，这将是 4GB，因此您的最大服务器内存设置应该是 12GB 而不是 15GB。
更多证据显示在您当前的内存分配中：您已打开内存中的锁定页面 (LPIM)，但您在内存中仅锁定了 12.02GB 的页面。这可能（但不能保证）意味着某些其他应用程序需要内存，因此 Windows 发出内存压力通知，SQL Server 放弃其他 3GB 内存让其他应用程序做它的事情。这更证明您不能真正使用 15GB 最大容量 - 您需要内存来存储其他东西。
当您的 SQL Server 承受外部内存压力并需要为其他应用程序释放内存时，您的计划缓存将受到影响。
所以你有几个选择：
好的，OP到这里，我终于通过将SQL Server 2016更新到最新版本解决了这个问题。我有SP1，昨天我安装了Cumulative Update 6.
我也像布伦特的回答所暗示的那样适当地设置了“最大内存”。顺便说一句，很好的答案，我敦促大家投票赞成。
已经 36 小时了，而且还在继续，计划没有被重置。
Brent Ozar 也有一个非常好的网站：https ://sqlserverupdates.com/来帮助确定您需要哪些更新。
另一件有帮助的事情是检测和解决“不受信任的外键”问题。布伦特有一篇非常好的文章（哈哈，是的，布伦特再次，我知道正确）关于如何解决它，只是谷歌，他是排名第一的结果