Tom那本oracle architecture中关于redo log论述的一个疑问,期待解答

zhangcj5

本人菜鸟一只,希望不要被大家笑话--

书中有这样一段论述
Virtually every operation you perform in Oracle generates some amount of redo to be written to the online redo log files. When you insert a row into a table, the end result of that insert is written to the redo logs. When you delete a row, the fact that you deleted that row is written.  when you drop a table, the effects of that drop are written to the redo log. The data from the table you dropped is not written; however, the recursive SQL that Oracle performs to drop the table does generate redo. For example, Oracle will delete a row from the SYS.OBJ$ table (and other internal dictionary objects), and this will generate redo, and if various modes of supplemental logging are enabled, the actual DROP TABLE statement will be written into the redo log stream.

中间标注红色部分"When you drop a table, the effects of that drop are written to the redo log. The data from the table you dropped is not written"我很疑惑.

这是的意思是drop table以后,那些table里面保存的数据没有被写入redo,这样的话,如果我想恢复这个table,里面的数据不是没法恢复吗?因为没有写入到redo log啊


比如我一年前drop了一个很大的table,一年以后想恢复这个表,因为drop的数据不再redo和archive里,所以即使我一年以来所有的redo和archive都在,这些数据不是都没办法回复了吗??

LuiseDalian

怎么就能确定tom写的就一定对，可以阅读官方文档中的相应部分

LuiseDalian

即使数据不在redo和archive里，但在drop表之前有一致的数据库备份，也可可以还原的。