Re: Parallel Server and Parallel Query

In article <331dfcca.17273582_at_WEIPROXY>, djetz_at_sierrasys.com says...
>
>First Question:
>
>When Oracle does a parallel query operation, how does it determine how
>to divide up the data between the query processors? Data location,
>data values? What?
>

OPS for the IBM SP/2 does have node affinity in 7.3. It'll make processes more likely to access data local to the node it's running on.

>Second Question:
>
>When using parallel server option, you must use raw devices. You
>create a logical volume on one physical disk or across many physical
>disks. If you create a lv across many physical disks and use this lv
>as the datafile when creating the tablespace, does Oracle know how
>many physical disks the tablespace spans? If it does, then how does
>it know?

This is completely transparent to Oracle. You can stripe at a hardware level, at a software level with a logical volume manager, or at an Oracle data file level. Oracle will always treat it like a single device.

>
>I ask this question because we are using the parallel server option
>and are considering using parallel query on some of our SQL. If
>Oracle can't detect the physical disks in a tablespace, then it might
>not be a good idea to use parallel query because it is really
>important to know where your data is sitting. Does anyone have
>experience with this?

That is the optimal case, but the parallel query features allow you to take better advantage of the disk and cpu resources in your cluster.

>
>Second Question, part 2:
>
>Has anyone done any Oracle striping on a raw device before? I know
>that this could be very expensive (disk-wise), but we may need to do
>it anyway. I would appreciate any comments on how you did this and
>any other experience you had with this.
The same rules apply as with a file system based database.

>
>I can receive e-mail and read this newsgroup, but I can't e-mail out
>from this site so I thank anyone in advance for any information they
>submit.
>
>Doris Jetz
>Consultant.
 

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