Plan Cache物件所提供的計數器,可監視 SQL Server 如何使用記憶體來儲存物件,例如預存程序、特定與備妥 Transact-SQL 陳述式,以及觸發程序。 可同時監視Plan Cache物件的多個執行個體,每個執行個體都代表所要監視的不同計畫類型。 下表描述SQLServer:Plan Cache計數器。
Plan Cache 对象提供用于监视SQL Server 如何使用内存来存储对象(例如存储过程、即席和准备的Transact-SQL语句以及触发器)的计数器。可同时监视 Plan Cache 对象的多个实例,每个实例代表一个要监视的不同类型的计划。 下表介绍了 SQLServer:Plan Cache计数器。 对象中的每个计数器均包含以下实例:...
若cacheobjtype为Compiled Plan,且objtype为Adhoc,则这个计划被考虑作一个Adhoc计划。在SQL Server 2005中,Adhoc计划偶尔被缓存,然而,即便缓存,你也无法重用该计划。当SQL Server从一个Adhoc查询中缓存计划时,缓存计划仅当被子序列处理准确匹配时才可重用。 示例数据库NorthWind2下载: http://www.sqlserverinternals...
Compiled plans are stored into a part of SQL Server's memory called plan cache. Plan cache is searched for possible plan reuse opportunities. If a plan reuse for a batch happens, its compilation costs are avoided. Note that in the SQL Server literature, the word "procedure cache" has been...
Finding a plan in cache is a two-step process. The hash key described previously leads SQL Server to the bucket in which a plan might be found, but if there are multiple entries in the bucket, SQL Server needs more information to determine if the exact plan it is looking for can be ...
计划缓存元数据(Plan Cache Metadata) 句柄(handle) sys.dm_exec_cached_plans视图为每个已编译计划包含一个值plan_handle。Plan_Handle是SQL Server从完整的编译计划中提取出的一个哈希值,它对当前的每一个已存在的编译计划是惟一的,可以被多次重用,可以被看作已编译计划的标识。如果批处理中的某个独立的语句被重...
WHERE cacheobjtype = 'Compiled Plan' ) AS ecpa PIVOT (MAX(ecpa.value) FOR ecpa.attribute IN ("set_options", "object_id", "sql_handle")) AS pvt; 不是所有的Set选项都引起重编译,下列Set选项改变时会引起重编译: 1、ANSI_NULL_DFLT_OFF ...
batch happens, its compilation costs are avoided. Note that in the SQL Server literature, the word "procedure cache" has been used to describe what is called "plan cache" in this paper. "Plan cache" is more accurate because the plan cache stores query plans of not just the stored ...
10.0 Plan Cache FlushArticle 01/17/2007 In SQL Server 2005, certain database maintenance operations or certain dbcc commands such as “dbcc freeproccache” or “dbcc freesystemcache” will clear the plan cache for the instance of SQL Server. Clearing the plan cache causes a recompilation of ...
MongoDB决定是否采用cache中的执行计划的条件是什么? 在有多个执行计划可选择的时候,MongoDB会选择一个最优的执行计划存放在cache中,MongoDB对同一类型的SQL(SQL基本一样,只有过滤条件具体的value不一样)会直接从cache中拿出执行计划,但是在采用cache之前也会进行判断是否继续采用cache中的执行计划。