Re: Documentation for reasons to NOT use RAC?
Date: Wed, 19 May 2010 10:12:48 +0530
Message-ID: <AANLkTin9IVG3Ca984mUWlQ6HAJ2QYw8le6UMYUPuFcLd_at_mail.gmail.com>
Yong .
Even if you dont specify the parallel hint in query, based on few heuristics ORACLE calculates if this query should be run in parallel mode or not and what the degree of parallelism it should have .Though this is possible only if auto DOP is enabled .
The decision to use parallel execution and the DOP chosen are based on the resource requirements of a statement. If the estimated elapse time for the statement is less than PARALLEL_MIN_TIME_THRESHOLD (default is AUTO which meaning 10 seconds) the statement will run serial.
Thanks ,
Anupam
On Wed, May 19, 2010 at 8:44 AM, Yong Huang <yong321_at_yahoo.com> wrote:
> > > I don't see how developers should write code differently
> >> if the code needs to be deployed to RAC.:
> >
> > Its not just being TAF/FAN aware, see Gints Plivna's comments
> > earlier in this thread.
>
> Tony,
>
> I understand Gints Plivna's and kathy duret's responses at
>
> http://www.freelists.org/post/oracle-l/Documentation-for-reasons-to-NOT-use-RAC,23
>
> They both proposed great ideas for application server admins. The only
> thing developers should do a little differently is perhaps "Use of parallel
> in queries to take advantage of the Rac power", but that's not really
> RAC-specific.
>
> In short, the developers don't need to do anything special for RAC. DBAs
> and mid-tier administrators do.
>
> Yong Huang
>
>
>
> --
> http://www.freelists.org/webpage/oracle-l
>
>
>
-- http://www.freelists.org/webpage/oracle-lReceived on Tue May 18 2010 - 23:42:48 CDT