由于表变量定义完毕以后,不支持对表变量结构的任何变更和索引创建,所以很多人会认为表变量不能创建索引,比如这篇文章SQL Server Temp Table vs Table Variable Performance Testing中的这句话“However, when we query rows using the indexed column of the temporary table, which is not indexed in the table va...
局部临时表(Local temp table)以#前缀来标识,并且只能被创建它的连接所使用.全局临时表(Global temp table)以##前缀来进行标识,并且可以和其它连接所共享.局部临时表局部临时表不能够被其它连接所共享的原因其实是在SQL Server 2000中自动为局部临时表的表名后面加上了一个唯一...
“A table variable is not a memory-only structure. Because a table variable might hold more data than can fit in memory, it has to have a place on disk to store data. Table variables are created in the tempdb database similar to temporary tables. If memory is available, both table vari...
Following are scenarios where temp table/variable are not cached: 1. select into #t 2. alter table #t 3. create index on #t 4. Global temp tables (##t) 5. Local temp tables on adhoc level (nest level 0) 6. table variables are also...
--Drop test temp tables DROP TABLE [##DimCustomer_test] DROP TABLE [#DimCustomer_test] 可以看到我们刚才创建的全局临时表名字并没有被加上标识. 表变量 表变量和临时表针对我们使用人员来说并没有什么不同,但是在存储方面来说,他们是不同的,表变量存储在内存中.所以在性能上和临时表相比会更好些!
Remove the DROP TABLE #tempSessionC statements from your code - optionally you can insert a DELETE FROM dbo.soSessionC statement, in case memory size is a potential concern D. Scenario: Table variable can be MEMORY_OPTIMIZED=ON A traditional table variable represents a table in the tempdb dat...
Remove theDROP TABLE #tempSessionCstatements from your code - optionally you can insert aDELETE FROM dbo.soSessionCstatement, in case memory size is a potential concern D. Scenario: Table variable can be MEMORY_OPTIMIZED=ON A traditional table variable represents a table in the tempdb database...
You can’t, for example, change the table definition after the initial DECLARE statement. In SQL Server 2000, a table variable can’t be the destination of a SELECT INTO statement or a INSERT EXEC (now fixed); You can’t call user-defined functions from CHECK constraints, DEFAULT values,...
CREATE TYPE my_type AS TABLE ...;,然后 DECLARE @mytablevariable my_type;。 B. 场景:替换全局 tempdb ##table 将全局临时表替换为内存优化的 SCHEMA_ONLY 表非常简单。 最大的改变是在部署时(而不是运行时)创建该表。 由于采用了编译时优化,创建内存优化表会比创建传统...
有关详细信息,请参阅 Faster temp table and table variable by using memory optimization(通过使用内存优化更快获得临时表和表变量)。 本机编译是指将编程构造转换为本机代码的过程,这些代码由处理器指令组成,无需进一步编译或解释。 内存中 OLTP 在创建内存优化表时编译内存优化表,并...