Re: DBWR

DBWR (database writer) only WRITES to the database files. It happens everytime
a database checkpoint event occures. DBWR keeps database buffer cache "clean" by taking "dirty" (modified) buffers and physicaly putting them into datafiles. DBWR is a background process (among others: SMON, PMON, etc).

Data reading from the database files is done by a server process spawned by a user session with dedicaded model or a pre-spawned by an instance with MTS model. This is a foreground process. Such a server process also writes data to database buffer cache as needed.

See the Oracle Server Concepts manual for detailes.

Hope it helps,
Eugene.

Ghassan William Shahwan <gshahwan_at_emirates.net.ae> wrote in message news:86v12i$ad32_at_news.emirates.net.ae...
> I have been reading two different Oracle books in the process of preparing
> for my OCP examination. One book says that the DBWR background process
 reads
> data from datafiles and eventually writes data to datafiles. The other
 book
> says that a "Foreground Server" process (not the DBWR) reads the data from
> datafiles and then the DBWR process writes any modified data back to the
> datafiles.
>
> The questions is : Which process READS from datafiles? Is it the DBWR or a
> "Foreground Server" process ? And does this change with an MTS
 configuration
> ? And finally if a "Foreground Server" process does read from datafiles,
> then what is the name of this process ?
>
> Any insight into this will be appreciated.
>
> Thanks to all,
> Gus
> P.S. Can future responses to this question be also copied to
> shahwan1_at_hotmail.com
>
>
>
Received on Sun Jan 30 2000 - 00:00:00 CST