HOW MYSQL USES INTERNAL TEMPORARY TABLES Table of Contents [hide] 1)UNION queries 2)Some views 3)SQL_SMALL_RESULT 4) Multiple-table UPDATE 5)Derived tables 6)subquery or semi-join 7)order by,group by,distinct 通过阅读MySQL的官方手册,我们可以知道出现下面情况的时候,MySQL可能会使用…

8.4.4 How MySQL Uses Internal Temporary Tables 这是MySQL手册中的一节,尝试补充了一些解释.用的版本是MySQL5.6.15社区版 In some cases, the server creates internal temporary tables while processing queries. Such a table can be held in memory and processed by the MEMORY storage en…

Temporary Tables and the TableType Property [AX 2012] 1 out of 1 rated this helpful - Rate this topic Updated: November 5, 2013 Applies To: Microsoft Dynamics AX 2012 R2, Microsoft Dynamics AX 2012 Feature Pack, Microsoft Dynamics AX 2012 从 Microsoft…

Temporary tables in SQL Server…

1简介 ORACLE数据库除了可以保存永久表外,还可以建立临时表temporary tables.这些临时表用来保存一个会话SESSION的数据, 或者保存在一个事务中需要的数据.当会话退出或者用户提交commit和回滚rollback事务的时候,临时表的数据自动清空, 但是临时表的结构以及元数据还存储在用户的数据字典中. 临时表只在oracle8i以及以上产品中支持. 2详细介绍 Oracle临时表分为 会话级临时表和事务级临时表. 会话级临时表是指临时表中的数据只在会话生命周期之中存在,当用…

Problem 许多时候, 我们想要Table Variables在动态SQL中执行,但现实是很骨感的.比如这个示例: DECLARE @sql_command NVARCHAR(MAX); DECLARE @parameter_list NVARCHAR(MAX); ) ); SELECT @sql_command = ' SELECT DISTINCT FirstName FROM Person.Person WHERE LastName IN (SELECT last_name FROM…

mysql官方的介绍 In some cases, the server creates internal temporary tables while processing queries. Such a table can be held in memory and processed by the MEMORY storage engine, or stored on disk and processed by the MyISAM storage engine. The server m…

MySQL has a number of global buffers, i.e. your SGA. There are also a number of per session/thread buffers that combined with other memory usage constitutes an unbounded PGA. One of the most common errors in mis-configured MySQL environments is the s…

好多人在调优Mysql的时候,总是对open_tables和opend_tables两个参数分别不清. 网上好多解释都是这样的:open_tables:当前打开表的数量opened_tables:当前已经打开表的数量 很简单的解释,可是这两句话看起来有点类似. 下面我来解释一下:open_tables:是当前在缓存中打开表的数量.opened_tables:是mysql自启动起,打开表的数量. 我们知道,假如没有缓存的话,那么mysql服务在每次执行一个语句的时候,都会先打开一个表.当sql语句…

MySQL查询产生临时表的分析 官网说明的地址:http://dev.mysql.com/doc/refman/5.5/en/internal-temporary-tables.html 参考:http://blog.csdn.net/chenchaoxing/article/details/25214397 In some cases, the server creates internal temporary tables while processing queries. Such a t…