Re: wither the checkpoint?

Jonathan Gennick heeft geschreven in bericht <37060596.14070120_at_netnews.worldnet.att.net>...
>I have an esoteric question on checkpoints that I need
>answered. The Oracle8 Backup & Recovery manual, under the
>heading "Managing Checkpoints", states the following:
>
> "A checkpoint identifies a redo log record such that all
>
> changes prior to the change pointed to by the checkpoint
>
> have been written to the datafiles by DBWn. "
>
>The way this sentence is written, it sounds as if the
>specific change pointed to by the checkpoint has NOT been
>written to the datafiles. Is that really true? Does anyone
>know for sure. Can anyone point me to a reliable reference
>that clarifies this?
>
>Jonathan

Your changes to the data are always written to the redolog files and rollback segments. When a checkpoint occurs, the data is written to the datafiles. In case of a crash, Oracle can reroduce your data from the redofiles and rollback segments. Oracle guarantees that data is safe on disk when you issue a commit. Because of the redo and rollback info, it is no problem that the datafiles are updated on a checkpoint. When you commit, everything is okay. Received on Fri Apr 02 1999 - 14:35:38 CST