Note in-line.
--
Regards
Jonathan Lewis
http://www.jlcomp.demon.co.uk
The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html
June 2004 UK - Optimising Oracle Seminar
July 2004 USA West Coast, Optimising Oracle Seminar
August 2004 Charlotte NC, Optimising Oracle Seminar
September 2004 USA East Coast, Optimising Oracle Seminar
September2004 UK - Optimising Oracle Seminar
"Howard J. Rogers" <hjr_at_dizwell.com> wrote in message
news:409334fa$0$25007$afc38c87_at_news.optusnet.com.au...
>
> After that I had indigestion with your 50-50 leaf block claim. Jonathan
> claims it's 50-50 *on average*, but not by volume, I think. Interesting.
>
I'm not sure I've ever been precise in my wording about how the 50/50
works - by default the tests I've done to date have always had uniform
sized keys, so 50/50 by key count would tend to be 50/50 by volume,
so I've never gone beyond saying just "roughly 50/50".
This, of course, demonstrates, that for every test result and repeatable
test case, there is always an enhancement to the test and refinement of
understanding. (Richard's "50% by volume" is such an obvious detail
to check - after it's been pointed out !! - it's also an extremely practical
point to be aware of, some systems will have keys with lots of columns
with lots of nulls, leading to all sorts of odd variation in key length).
In fact, Steve Adams described a further detail to the split process when
he was doing the Miracle Masterclass in Denmark in 2003, the preliminary
target is a 'fair' split - which Richard now tells us is 50/50 by volume -
but
Oracle will then allow a little side-stepping on the split to mimimise the
size
of the necessary entries in the branch blocks.
Received on Sat May 01 2004 - 03:30:14 CDT
