After the loss
of the instance, the background process SMON automatically performs instance recovery
when the database is reopened. Instance recovery consists of the following steps:
1. Rolling forward to recover data that has not been recorded in the data files but that has
been recorded in the online redo log. This data has not been written to disk because of
the loss of the SGA during instance failure. During this process, SMON reads the redo
log files and applies the changes recorded in the redo log to the data blocks. Because all
committed transactions have been written to the redo logs, this process completely
recovers these transactions.
2. Opening the database so that users can log on. Any data that is not locked by
unrecovered transactions is immediately available.
3. Rolling back uncommitted transactions. They are rolled back by SMON or by the
individual server processes as they access locked data.
最初由 chenyan995 发布
[B]After the loss
of the instance, the background process SMON automatically performs instance recovery
when the database is reopened. Instance recovery consists of the following steps:
1. Rolling forward to recover data that has not been recorded in the data files but that has
been recorded in the online redo log. This data has not been written to disk because of
the loss of the SGA during instance failure. During this process, SMON reads the redo
log files and applies the changes recorded in the redo log to the data blocks. Because all
committed transactions have been written to the redo logs, this process completely
recovers these transactions.
2. Opening the database so that users can log on. Any data that is not locked by
unrecovered transactions is immediately available.
3. Rolling back uncommitted transactions. They are rolled back by SMON or by the
individual server processes as they access locked data. [/B]
想起来了，这个是ＳＧ上的一段话，不过以前就有一点疑问
是先前滚，然后用户登陆，但是这个时候就有点不明白了，就是有一些用户没有ＣＯＭＭＩＴ的资料，但是这些资料已经写到磁盘，那在系统回滚之前，这些资料就可以被用户查询出来，这样就可能出现一些报表上的错误．．．．．．．．．．．．．．
