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Re: re-indexing per statement or per row?

From: Sean M <smckeownNO_at_BACKSIESearthlink.net>
Date: Mon, 08 Apr 2002 16:10:04 GMT
Message-ID: <3CB1C0E6.C382A467@BACKSIESearthlink.net>


Thomas Kyte wrote:
>
> "Niall says...
> >
> >"Connor McDonald" <connor_mcdonald_at_yahoo.com> wrote in message
> >>
> >> And just to reinforce Tom's point - from a shopping web site
> >>
> >> (IDE) disk 160G £205
> >> (SCSI) disk 36.9GB £258.50
> >>
> >> You don't get a lot of developer time for £250
> >
> >Food for thought this whole discussion. On the whole I don't like throwing
> >hardware at problems which this approach *could* be viewed as On the other
> >hand there is an argument that you are just buying an 'appropriate' level of
> >hardware for the task.
> >
>
> That's just not the right approach. You size UNDO and REDO based on your
> workloads, not based on what "feels good". The argument that "disk is an
> expense, we must be cautious in our purchase of it" just doesn't work. Compared
> to the level of effort you will spend over the life of your system working
> around NOT having sufficient disk allocated to these important structures -- the
> disk is almost FREE.
>
> While 9i gives us resumable statements, partially fixing the problem -- I just
> wonder how many millions of hours have be wasted by people doing something and
> having temp or rollback blow out "because they don't feel it should take that
> much".
>
> It is penny wise, pound foolish to skimp in this area.

While I agree w/Tom that's it's usually a bad use of time/money to skimp on disk for temp/rollback/redo, the frequent assertion (not Tom's, but on this newsgroup and elsewhere) that "disk is cheap" in the context of a regular datafile doesn't always hold water. Consider a large production database, triply mirrored on EMC or equivalent. Add in four or five copies of that database for standby, reporting, testing, development, upgrading, etc., each of which is mirrored as well and requires tape backup services, and that one gig datafile you added just cost the company $10,000. Disk is often the biggest expense in a production datacenter. Judicious space management is still relevant, even in today's cost-cutting world of hard disk technology.

Regards,
Sean Received on Mon Apr 08 2002 - 11:10:04 CDT

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