Re: Number of extents related with performance?

In article <3a4c152e_at_news.iprimus.com.au>,   "Howard J. Rogers" <howardjr_at_www.com> wrote:
>
> "David Fitzjarrell" <oratune_at_aol.com> wrote in message
> news:92gg5k$3r2$1_at_nnrp1.deja.com...
> [Snip]
> >
> > The old 'hard and fast' rules for extents are as follows:
> >
> > 2k block size 121 extents
> > 4k block size 249 extents
> > 8k block size 505 extents
> >
>
> Damn! You're right, David -clearly I'm going senile in my middle age!
> (though I *was* close!!)
>
> > There is some logic to the extent maximums; starting with the 2k
 block
> > size (the minimum allowed) the next block size will contain (2*old
> > extents) + 7:
> >
> > 4k max = 2(121) + 7 = 242 + 7 = 249
> > 8k max = 2(249) + 7 = 498 + 7 = 505
> >
> > Extrapolating to a 16K block size should provide a maximum of 1,017
> > extents (a value I have not verified, although the previous values
> > posted have been validated).
> >
>
> Yup, 1017 looks spookily familiar.
>
> > This may not be a rigorous mathematical proof (it has been quite
 some
> > time since I have dealt with Eigenvalues) but the calculation
 provides
> > the correct number of expected extents given the 'power of 2' block
> > sizes usually implemented.
> >
>
> Last time I dealt with Eigenvalues, I sent them packing... when last
 heard
> of, they'd taken up residence at the local bar, and were downing
 beers by
> the Stein. Dodgy lot, if you ask me.
>
> Regards
> HJR
>
> > --
> > David Fitzjarrell
> > Oracle Certified DBA
> >
> >
> > Sent via Deja.com
> > http://www.deja.com/
>
>

Obviously you gave them MY address, as I have been frantically attempting to entertain them for the past three days. Quite a difficult group to appease -- don't attempt to do so without a professional present.

Worry not about senility, Howard -- each of us has had the dubious honor of saying 'Well, I was close...' at one time or another, myself likely more times than necessary (or at least it feels that way). I attribute it to what my spouse lovingly refers to as 'brain farts', and, according to all substantial authorities ('substantial' meaning female) the male of the species is prone to such occurrences.

Take heart that the TRUE MILLENIUM is fast approaching. Hopefully, through some magical intervention, all will become right with the world and the only databases will be Oracle databases.

If marriage were only that easy.

--
David Fitzjarrell
Oracle Certified DBA


Sent via Deja.com
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