Re: separate data/inidex

On 21 Apr 2002, tkyte_at_oracle.com wrote:

> The odds of the heads "remaining" in place is sort of silly as well.

Can you explain how it is that parallel helps performance? I thought parallel meant that a particular set of rowids where given to a query slave while another set to another query slave and those slaves went and got all the data between there respective ids. If they can do so without the head jumping around from request to request (ie, on separate disks and no other read requests), then that will be most optimal. But if they can't, which is on every multi-user system and/or disk array out there, then how does parallel speed things up? Is it based mainly on the fact that there are more cpus being utilized in going after a particular set of data? More instructions for the parallel read are being sent and therefore executed?

PQ1 asks CPU1 which asks arrayA for some data, PQ2 asks CPU2 which asks arrayA for some data, back and forth ... If it wasn't in parallel, then only process1 would ask CPU1 which would be asking arrayA for some data while other processes would be asking CPU2 which would ask arrayA for some data?

-- 
Galen deForest Boyer
Sweet dreams and flying machines in pieces on the ground.