MVCC当中的版本是基于tid的,在开启了MVCC模式之后,每一条record会生成两个sys_field,分别存储begin和end,来标识一个事务的可见性,这里似乎并没有一个统一的标准,只要能满足MVCC协议本身的要求即可,在Miniob当中的设置如下: record通过begin和end 两个id进行状态管理,begin用于表示事务开始的时间,end为事务结束的时间,...
a dozen individual teams and roughly the same amount of team sports including men’s and women’s basketball, bowling, cross country, golf, indoor track, lacrosse, soccer, tennis and track & field. Additionally, men may play baseball and ice hockey and women may play softball and volleyball...
Thefree space mapis a fork that keeps track of the availability of free space inside pages. This space is constantly changing: it decreases when new versions of rows are added and increases during vacuuming. The free space map is used during insertion of new row versions in order to quickly...
When an insert is being performed, the transaction is yet unaware of whether it will be completed successfully. And at the commit time it's already unclear which rows and in which pages were changed. There can be a lot of such pages, and it is impractical to keep track of them. Besides...
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