Re: Does a commit cause a checkpoint?

Ryan wrote:

> what happens if there is a checkpoint. DBWR and LGWR start writing to disk
> at the same time. Or is commit is issud.
>
> while both DBWR and LGWR are writing the same SCN to disk we have an
> instance failure.
>
> now since all of LGWR is not safely in the redo log, the data is not
> considered committed. HOWEVER,. DBWR has already started writing to the
> datafile thereby CHANGING what is in the datafile.
>
> how does oracle recover this? Does it use rollback? it cant roll forward
> since all the data is not in the redo logs.

(Sigh)

(With this kind of FUD, one could suspect you of trolling for ... [name of favorite Oracle RDBMS competitor] <g> )

Please consider reading the appropriate section in the Concepts manual.

Manual is "Oracle9i Database Concepts, Release 2 (9.2), Part Number A96524-01", Chapter is "8 Process Architecture", Section is "Oracle Processes Overview", subsection is "Log Writer Process (LGWR)"., URL is http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96524/c09procs.htm#3158

When I read it, it answers this question as well, at least to my satisfaction ... Received on Wed Jun 18 2003 - 22:31:47 CDT