redo的内部过程与lgwr
Oracle采用混合日志记录模式,以数据块为单位,即dba + sql,即避免记录整个块,又可快速恢复the granularity is at the block level (like physical logging), so one operation is stored for each individual block change一个大事务可由多个mini-transaction即redo record组成,而每个record又可由多个change ...