Re: Index rebuilding

Sorry,
Didn't quite finish before hitting <ret>

: It would be an interesting experiment to see if there
: is any sort of general visual image that people use in
: response to the word "unbalanced". I suspect that
: many people would think of a set of old-style scales
: with one side hanging down further than the other.
: Conversely, I don't think many people would have
: an image of (something like) a plank tipping because
: a fulcrum was off-centre.
:

Apply these images to the expression 'unbalanced indexes', and I think you'll agree that the more (likely to be) popular image is exactly the wrong one for B-trees, and the (probably) less popular one is nearly an adequate one.

Regards

Jonathan Lewis

http://www.jlcomp.demon.co.uk/faq/ind_faq.html The Co-operative Oracle Users' FAQ

http://www.jlcomp.demon.co.uk/seminar.html Optimising Oracle Seminar - schedule updated Sept 19th

• Original Message ----- From: "Jonathan Lewis" <jonathan_at_jlcomp.demon.co.uk> To: <oracle-l_at_freelists.org> Sent: Saturday, November 13, 2004 8:36 AM Subject: RE: Index rebuilding

:
: Regarding specifically the sentence:
:
:
:: So if you're looking at the diagram
with
: a whole
:: pile of 25% full or 50% full buckets toward the left and all full or
: nearly
:: full buckets toward the right, I'd call that unbalanced.
:
:
: You shouldn't.
:
: When talking about "Balanced B-trees", you need to honour
: the technical meaning of word "Balanced" in the context that is
: being used, otherwise you confuse the issue.
:
:

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