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...