If you want rules of thumb, then take CPU_COUNT+1 up to CPU_COUNT *2. I think LIO & PIO ratio is irrelevant, the most important is whether you are able to construct optimal parallel execution plan, e.g. avoid excessive parallel slave messaging & waiting. This is mostly design and SQL issue.
The number mount points is irrelevant novadays as well IMHO, especially when you're using async IO, SANs & SAME like architecture. The only thing what comes into my mind where splitting into mount points (thus different file systems) helps performance wise, is that with more file systems you got more file system locks and you can spread contention for these locks that way. Tanel. ----- Original Message ----- To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]> Sent: Thursday, September 18, 2003 9:34 PM > i know there are no magic formulas, but im hoping for something better than trial and error. i would assume that parallel query helps most when: > > 1. are doing work off of multiple mount points. > 2. Have alot more LIOs to perform than PIOs(such as sorts). > > am i close on this? > > > > From: "M Rafiq" <[EMAIL PROTECTED]> > > Date: 2003/09/18 Thu PM 01:34:44 EDT > > To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]> > > Subject: Re: max parallel query > > > > Tanel, > > You are right. There is a param parallel_automatic(I don't remember exact > > name as I don't have access to database) which should be set to true and let > > system decide how many pq slave to be used. For max_parallel_server default > > is 5 and can be set to higher number which memory and cpu can handle. It > > is faster because it uses all system resources at a given time. > > > > Rarallel process can be used for large batch jobs during off-peak time. > > > > Regards > > Rafiq > > > > > > Reply-To: [EMAIL PROTECTED] > > To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]> > > Date: Thu, 18 Sep 2003 08:39:44 -0800 > > > > There is no simple magic formula how many parallel slaves you should have. > > It all depends on your CPU and IO utilization. Yes, utilization, because if > > your CPUs or IO are running at their limits already, you won't benefit from > > parallel execution at all. In fact PX may make the situation even worse, > > because it's designed to give you the results the fastest way, not the most > > efficient way. > > > > Tanel. > > > > ----- Original Message ----- > > To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]> > > Sent: Thursday, September 18, 2003 6:15 PM > > > > > > > We run multiple instances on the same server. My understanding is > > max_parallel_servers should be set to 4 x CPU. We have 4 CPUs which means > > 16. > > > > > > however, does this take into account multiple instances on the same > > server? > > > > > > > > > -- > > > Please see the official ORACLE-L FAQ: http://www.orafaq.net > > > -- > > > Author: <[EMAIL PROTECTED] > > > INET: [EMAIL PROTECTED] > > > > > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com > > > San Diego, California -- Mailing list and web hosting services > > > --------------------------------------------------------------------- > > > To REMOVE yourself from this mailing list, send an E-Mail message > > > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > > > the message BODY, include a line containing: UNSUB ORACLE-L > > > (or the name of mailing list you want to be removed from). You may > > > also send the HELP command for other information (like subscribing). > > > > > > > > > -- > > Please see the official ORACLE-L FAQ: http://www.orafaq.net > > -- > > Author: Tanel Poder > > INET: [EMAIL PROTECTED] > > > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com > > San Diego, California -- Mailing list and web hosting services > > --------------------------------------------------------------------- > > To REMOVE yourself from this mailing list, send an E-Mail message > > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > > the message BODY, include a line containing: UNSUB ORACLE-L > > (or the name of mailing list you want to be removed from). You may > > also send the HELP command for other information (like subscribing). > > > > _________________________________________________________________ > > Send and receive larger attachments with Hotmail Extra Storage. > > http://join.msn.com/?PAGE=features/es > > > > -- > > Please see the official ORACLE-L FAQ: http://www.orafaq.net > > -- > > Author: M Rafiq > > INET: [EMAIL PROTECTED] > > > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com > > San Diego, California -- Mailing list and web hosting services > > --------------------------------------------------------------------- > > To REMOVE yourself from this mailing list, send an E-Mail message > > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > > the message BODY, include a line containing: UNSUB ORACLE-L > > (or the name of mailing list you want to be removed from). You may > > also send the HELP command for other information (like subscribing). > > > > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.net > -- > Author: <[EMAIL PROTECTED] > INET: [EMAIL PROTECTED] > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com > San Diego, California -- Mailing list and web hosting services > --------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an E-Mail message > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > the message BODY, include a line containing: UNSUB ORACLE-L > (or the name of mailing list you want to be removed from). You may > also send the HELP command for other information (like subscribing). > -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Tanel Poder INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
