Setting AUTO_UPDATE_STATISTICS to OFF can cause suboptimal query plans and degraded query performance. Setting the AUTO_UPDATE STATISTICS option to ON is recommended. Up to SQL Server 2014 (12.x), the Database Engine uses a recompilation threshold based on the number of rows in the table or...
查询计划中的联接顺序为 Table1、 Table2、 TableA、 TableB、 Table3。解析视图的索引与任何索引相同,仅当查询优化器确定在 SQL Server 的查询计划中使用索引视图有益时,SQL Server 才会选择这样做。索引视图可以在任何版本的 SQL Server 中创建。 在某些较早版本的 SQL Server 中,查询优化器会自动考虑索引视图...
下面两段代码虽然结构一模一样,但是因为参数值不同,SQL SERVER选择了不同的执行计划,下图,这是因为SQL SERVER知道一个只会返回3行(EstimateRows), 而后一个会返回 121317行,这里SQL SERVER 猜得是完全正确的。 SETSTATISTICSPROFILEONSELECTB.SalesOrderID , B.OrderDate , A.*FROMdbo.SalesOrderDetail_TEST AINNE...
Setting AUTO_UPDATE_STATISTICS to OFF can cause suboptimal query plans and degraded query performance. Setting the AUTO_UPDATE STATISTICS option to ON is recommended. Up to SQL Server 2014 (12.x), the Database Engine uses a recompilation threshold based on the number of rows in the table or...
Setting AUTO_UPDATE_STATISTICS to OFF can cause suboptimal query plans and degraded query performance. Setting the AUTO_UPDATE STATISTICS option to ON is recommended. Up to SQL Server 2014 (12.x), the Database Engine uses a recompilation threshold based on the number of rows in the table or...
A statistics object is considered out of date in the following cases: If the statistics is defined on a regular table, it is out of date if: The table size has gone from 0 to >0 rows (test 1). The number of rows in the table when the statistics were gathered was 500 or less, ...
D. Scenario: Table variable can be MEMORY_OPTIMIZED=ON Show 4 more Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance If you use temporary tables, table variables, or table-valued parameters, consider conversions of them to leverage memory-optimized tables and table variables...
Up to SQL Server 2014 (12.x), the Database Engine uses a recompilation threshold based on the number of rows in the table or indexed view at the time statistics were evaluated. The threshold is different whether a table is temporary or permanent. הרחב טבלה Table ...
Up to SQL Server 2014 (12.x), the Database Engine uses a recompilation threshold based on the number of rows in the table or indexed view at the time statistics were evaluated. The threshold is different whether a table is temporary or permanent. Rozbaliť tabuľku Table typeTable ...
SQL Server优化的方法<一> 查询速度慢的原因很多,常见如下几种: 1、没有索引或者没有用到索引(这是查询慢最常见的问题,是程序设计的缺陷) 2、I/O吞吐量小,形成了瓶颈效应。 3、没有创建计算列导致查询不优化。 4、内存不足 ...