Re: IMP/EXP accross platforms: What will be missing?

ydias_at_hotmail.com (dias) wrote:

>Hi,
>
>Objects are created before the import, no grant problems (step 5).

OK

>Why do you think that FTS will run faster if you import objects serially ?

If importing serially, extents will be allocated so that they will be physikally contiguous on the harddisk. When performing FTS on a segment composed of those extents, the harddisk head won't have to jump around.

If doing it in parallel, extents from different segments will be mixed up as they are written one after the other. A FTS will lead to heavy movements of the harddisk head in order to chase the right extents, since some of them will be skipped.

I assume that neither an oracle data file nor the segments contained therein will be necessarilly written in one undivided chunk of space. Oracle has no control about this, it is the operating system who decides (raw devices are different, of course). But again, I am not absolutely sure about this.

Interesting point. I don't think that I will be able to investigate this particular question practically.

Perhaps someone more experienced will contribute his opinion.

Rick Denoire Received on Tue Nov 04 2003 - 16:45:22 CST