RE: SMP/MPP and PQO

According to this PQO provides benefits even on a single CPU machine:

http://www.orafaq.com/faqopq.htm#ONECPU

I can see how it would if you had most of the records in your cache, so half the query could be worked on while the other half was retrieving the records from the disk, but this wouldn't happen very often. Alternatively, if you had cunning partitions across multiple mount points, and your hardware was capable of exploiting that. Hmmm.

g.

"Koivu, Lisa" <lisa.koivu_at_efairfield.com> Sent by: root_at_fatcity.com
06/12/01 09:17 AM
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        Subject:        SMP/MPP and PQO

Hello everyone,
I was reading up on the differences between SMP, MPP and how they may affect PQO (Parallel Query).
My understanding is that MPP is a host with defined domains (like an e10k with virtual machines on it).  SMP is a standalone host with no domains and multiple processors.  I am not considering clustering here. It seemed to me the only requirement that you really need to run PQO is to have available resources to power it.  For example, a little 2-cpu box that is pinned a majority of the time is only going to suffer if PQO is turned on.  However, if we had a 16-cpu box with abundant resources, turning on PQO would help fts and large index scans in a dw-type environment.  (At least this is what I saw in the past).  
Also, I was taught that PQO should not be used when a table/index is not partitioned.  However, upon reading the doco, it states that the slaves split up work by blocks (or was it extents?).  Seems to me this could cause more problems than it's worth (i/o contention?) and partitioning, if done carefully, would be the smarter way to go.  Would the slaves really be smart enough to divy up work intelligently on a non-partitioned object?  My initial thought is NO.  
In addition, on metalink they even went so far as to state it is OK to use PQO on a 2-processor NT machine.  Seems to me the statement that 'PQO provides no benefit on a SMP machine' is not warranted, unless Oracle Support was just pacifying the customer who wanted to see PQO work. Maybe my idea of SMP is too simple.  If I am off my rocker can someone please set me straight?
Thanks
Lisa Koivu
Oracle Database Administrator
954-935-4117
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