RE: Tables and indexes on different disks

What about when writing data to the table, table and index are accessed the same time.

Alex.

> -----Original Message-----
> From: Connor McDonald [mailto:hamcdc_at_yahoo.co.uk]
> Sent: Tuesday, March 13, 2001 6:27 PM
> To: Multiple recipients of list ORACLE-L
> Subject: Re: Tables and indexes on different disks
>
>
> That argument is incorrect, but then again, so is the
> argument that they must be separated.
>
> (IMHO) What really matters is having a good grasp of
> what I/O is happening on your db and spreading the I/O
> accordingly.
>
> For example, for nested loop type of access, the
> table/index separation will probably give a gain. For
> a sort merge, then separating the tables involved is
> more important (since the indexes in this case may not
> be used at all).
>
> Then throw in index fast full scans, hash joins,
> parallel slaves et al and things get all the more
> complicated.
>
> I think the *intentions* behind all the tuning doco we
> all typically see is valid - namely, try to control
> and balance your I/O.
>
> Cheers
> Connor
>
> --- Michal Zaschke <zaschke_at_suas.cz> wrote: > Hi all,
> >
> > I've read an interesting section in Oracle Docu
> > (Tuning I/O):
> >
> > ---
> > Separating Tables and Indexes
> >
> > It is not necessary to separate a frequently used
> > table from its index.
> > During the course of a transaction, the index is
> > read first, and then
> > the table is read. Because these I/Os occur
> > sequentially, the table and
> > index can be stored on the same disk without
> > contention.
> > ---
> >
> > Why do you then recommend to separate tables and
> > indexes to different
> > disks?
> >
> > Thanks
> > Mike
> > --
> > Please see the official ORACLE-L FAQ:
> > http://www.orafaq.com
> > --
> > Author: Michal Zaschke
> > INET: zaschke_at_suas.cz
> >
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> =====
> Connor McDonald
> http://www.oracledba.co.uk
>
> "Some days you're the pigeon, some days you're the statue"
>
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-- 
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-- 
Author: Berindei Alex
  INET: Alex.Berindei_at_elsag.it

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