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Re: Oracle's Myth: keep tables and indexes in separate tablespaces

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Sat, 11 Oct 2003 15:03:37 +0100
Message-ID: <bm92im$5u$1$830fa795@news.demon.co.uk>

Good test - which exhibits an interesting point: when you quadrupled the number of discs, you only doubled the performance.

Of course, the conclusions you may draw
from the test depend on the activity - but it does suggest that there is mileage in thinking carefully about how to make best use of the available spindles.

Possible explanations that could fit your observation:

    Your test was read only, so the spindles     for undo and redo were effectively inactive     so the effective spindle count was only     doubled.

    Your test was I/O bound on one disc, but     required only a little extra I/O capacity to     become CPU bound

    Your test was write-intensive, but you had     lots of indexes on the updated tables, so the     index-holding disc became the I/O bottleneck     before you go close to capacity on the other     three.

    Your test was highly concurrent with lots of     very small updates on tables that did not     affect indexes - so your bottleneck was in     the redo log allocation and redo log buffer.

--
Regards

Jonathan Lewis
http://www.jlcomp.demon.co.uk

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"Geomancer" <pharfromhome_at_hotmail.com> wrote in message
news:cf90fb89.0310100430.7c362905_at_posting.google.com...

> In my experience with Oracle on Windows, I demonstrated significant
> slowdown with the whole database on a single non-RAID disk.
>
> When I moved indexes to a separate disk, undo to another and redo to
a
> 4th disk, performance doubled!
>
Received on Sat Oct 11 2003 - 09:03:37 CDT

Original text of this message

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