Re: Oracle 8.1.7 huge performance problem : please help !

kouchba_at_yahoo.com (kouchba) wrote in news:f55a8ec8.0401140345.17e23c71 @posting.google.com:

> Hi there,
>
> We are using Oracle 8.1.7 on Solaris 7 and Oracle 7.3.4 as well.
> We compared the execution plan of a query under Oracle 7 and Oracle
> 8.1.7 and it is exactly the same (using the same indexes,..). The
> number of extents of the index is the same too. The data files of the
> two instances are located on the same disks. But each time we execute
> the query under Oracle 8 , it is about ten times slower. That
> slowliness is not related to that particular query but to the whole
> application when executed under Oracle 8.1.7. So I am thinking more of
> an instance problem rather than an application problem.
>
> It seems to be IO bound to me just as something which have changed in
> the way Oracle 8 interacts with the filesystem. I tried to play with
> the hidden parameter _filesystemio_options but it did not work.
>
> Any idea ?
>
> Thanks,
> Philippe (kouchba_at_yahoo.com, pbackouche_at_sepro-robotique.com)
>

First thing to do is look at the wait events and verify that i/o really is the problem. If it is check the following.

Are you getting more i/o requests on the 8i instance, or are the i/o's taking longer?

Are both instances on the same machine? If not the problem could be in the o/s or hardware. Do both machines have the same number of controllers? Is one of them sharing band width with another application where the other is not.

I am not as familiar with Solaris as I am with other platforms. Does it support asynch i/o? If so is it possible aio is enabled on the v7 instance but not on the 8i one? Are the other i/o parameters (block size, multiblock read count, etc.) configured the same.

-- 
Chuck
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