为了更好地理解 SQL Server 中的查询缓存及其结构,以下是对应的类图,使用mermaid语法构建的。 SQLServer+User+Database+QueryCache+ExecutionPlanUser+login()+executeQuery()Database+createTable()+insertData()QueryCache+addPlan()+removePlan()+clearCache()ExecutionPlan+optimize()+execute() 结尾 在本文中,我们...
SQL Server提供了一个系统功能DBCC FREEPROCCACHE去清理执行计划缓存,参数是上文提到的具体的执行计划句柄(plan_handle),不加参数就全清了,注意一下即可。 --Remove the specific plan from the cache.清除特定的执行计划DBCCFREEPROCCACHE (0x060006001ECA270EC0215D05000000000000000000000000);GO 对于DBCC FREEPROCCACHE去...
As an application, SQL Server may request system resources as it executes a query andwaitsfor its request to be completed. These waits are represented by SQL Server wait statistics. SQL Server tracks wait information any time that a user connection or session_id is waiting. This wait informatio...
Query Store is enabled by default for newly created databases as of SQL Server 2022 CTP 2.1. Parameter sensitive plan optimization Automatically enables multiple, active cached plans for a single parameterized statement. Cached execution plans accommodate largely different data sizes based on the ...
示例:SQL Server A. 从计划缓存中清除查询计划 以下示例通过指定查询计划句柄从计划高速缓存中清除查询计划。 为了确保示例查询在计划高速缓存中,首先执行该查询。 将查询sys.dm_exec_cached_plans和sys.dm_exec_sql_text动态管理视图以返回查询的计划句柄。
Execution plans for any specific query in SQL Server typically evolve over time due to a number of different reasons such as statistics changes, schema changes, creation/deletion of indexes, etc. The procedure cache (where cached query plans are stored) only stores the latest execution plan. Pl...
Microsoft SQL Server 2005技术内幕 查询、调整和优化笔记 hash union,hash aggression,hash join 聚合aggression:标量聚合(流聚合实现),流聚合,哈希聚合 联合union union all:哈希联合,merge join sqlserver会把哈希聚合和流聚合混合在一起使用 哈希聚合(哈希匹配是不需要先排序的,除非强制排序 强制加order by 无论哈...
33ExceptionIndicates that an exception has occurred in SQL Server. 34SP:CacheMissIndicates when a stored procedure isn't found in the procedure cache. 35SP:CacheInsertIndicates when an item is inserted into the procedure cache. 36SP:CacheRemoveIndicates when an item is removed from the procedure...
optimize for ad hoc workloads Server Configuration Option FORCED PARAMETERIZATIONEntries in the plan cache are evicted because of growth in other caches or memory clerks. You might also encounter plan cache eviction when the cache reaches its maximum number of entries. In addition to trace flag 8032...
along with one I haven't yet mentioned: dm_exec_cached_plans. This DMV also contains details about query plans that have been cached by SQL Server. As you can see, the results provide the number of times a plan has been used (the Plan usage column), the individual query, the parent ...