For a SQL Server database set at compatibility level 120 and above, the legacy cardinality estimator (CE version 70) can be activated at the database level by using the ALTER DATABASE SCOPED CONFIGURATION.SQL Copy ALTER DATABASE SCOPED CONFIGURATION SET LEGACY_CARDINALITY_ESTIMATION = ON; GO ...
For a SQL Server database set at compatibility level 120 and above, the legacy cardinality estimator (CE version 70) can be activated at the database level by using theALTER DATABASE SCOPED CONFIGURATION. SQL ALTERDATABASESCOPED CONFIGURATIONSETLEGACY_CARDINALITY_ESTIMATION =ON; GOSELECTname,valu...
For a SQL Server database set at compatibility level 120 and above, the legacy cardinality estimator (CE version 70) can be activated at the database level by using the ALTER DATABASE SCOPED CONFIGURATION.SQL Kopiera ALTER DATABASE SCOPED CONFIGURATION SET LEGACY_CARDINALITY_ESTIMATION = ON;...
In addition, some expressions that aren't constant folded but whose arguments are known at compile time, whether the arguments are parameters or constants, are evaluated by the result-set size (cardinality) estimator that is part of the optimizer during optimization....
The following example applies the hint to force thelegacy cardinality estimatorto query_id 39, identified in Query Store: SQL EXEC sys.sp_query_store_set_hints @query_id= 39, @query_hints = N'OPTION(USEHINT(''FORCE_LEGACY_...
EXEC sys.sp_query_store_set_hints @query_id= 39, @query_hints = N'OPTION(USEHINT(''FORCE_LEGACY_CARDINALITY_ESTIMATION''))'; 以下示例应用提示,以强制实施最大内存授予大小(在配置的内存限制中PERCENT为query_id39),该限制在查询存储中标识: ...
在SQL Server中,我们要看懂执行计划和统计信息,我们可能需要深刻理解一些关键词,例如密度(Density)、选择性(Selectivity)、谓词(predicate)、基数(Cardinality)。前阵子,对密度和选择性的概念模糊了,刚好看了Query Tuning Fundamentals: Density, Predicates, Selectivity, and Cardinality这篇文章, 遂结合自己的理解、以及...
https://docs.microsoft.com/en-us/sql/relational-databases/performance/cardinality-estimation-sql-server?view=sql-server-2017 https://blogs.msdn.microsoft.com/psssql/2015/06/16/identifying-sql-server-2014-new-cardinality-estimator-issues-and-service-pack-1-improvement/...
The following example applies the hint to force thelegacy cardinality estimatorto query_id 39, identified in Query Store: SQL EXEC sys.sp_query_store_set_hints @query_id= 39, @query_hints = N'OPTION(USEHINT(''FORCE_LEGACY_CARDINALITY_ESTIMATION''))'; ...
注意:如果数据库兼容性级别低于 120,则启用跟踪标志 2312 将使用基数估计模型 SQL Server 2014 (12.x) (120)。 有关详细信息,请参阅 查询提示。从SQL Server 2016 (13.x) Service Pack 1 开始,若要在查询级别完成此操作,请添加USE HINT 'FORCE_DEFAULT_CARDINALITY_ESTIMATION'查询提示,而不是使用此跟踪标志...