From my testing, I have found the following autoallocate alogrithm. The
first 16 extents are 64k in size. The subsequent allocation method is
the next 63 extents of 1m, the next 120 extents of 8m and all additional
extents at 64m. I have tested this with segments in excess of 100
gigabytes and I did not find a new extent size. The first 3 sizes are
documented by Oracle, the last one I found by testing and have verified
from other research, though the author/website escapes me at the current
time.
--
Daniel W. Fink
http://www.optimaldba.com
IOUG-A Live! April 27 - May 1, 2003 Orlando, FL
Sunday, April 27 8:30am - 4:30pm - Problem Solving with Oracle 9i SQL
Wednesday, May 1 1:00pm - 2:00pm - Automatic Undo Internals
Jamadagni, Rajendra wrote:
> Rachel,
>
> in case of auto allocate, oracle used 4 or 5 (experts don't even agree
> on if it is 4 or 5) fixed sizes (64k ...) and based on number of
> existing extents it will choose when an extent of next size should be
> allocated. The problem is there is no set formula (or I haven't seen
> one agreed upon by Oracle ... the answer from Oracle is always fuzzy
> about this).
>
> That's why, I don't know if the next extent of my table will be 64K or
> 1M ... if someone knows a formula, I can write a quick script and
> things would be easy ... but due to lack of formula, everything is a
> hypothesis ..
>
> In case of dictionary managed, you have next extent size and pct
> increase and you can predict what the next extent would be. This is
> also true if you use uniformed extents in LMT. But it isn't easy in
> LMT and auto allocate. It is probably as predictable as expecting a
> straight like from a drunken monkey with a crayon.
>
> Raj
> -------------------------------------------------------------
> Rajendra dot Jamadagni at espn dot com
> Any views expressed here are strictly personal.
> QOTD: Any clod can have facts, having an opinion is an art !!
>
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>
>
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Author: Daniel W. Fink
INET: optimaldba_at_yahoo.com
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Received on Mon Mar 10 2003 - 13:25:31 CST
