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From aaron morton <aa...@thelastpickle.com>
Subject Re: b-tree
Date Fri, 22 Jul 2011 09:13:49 GMT
You can use something like Zoo Keeper to coordinate processes doing page splits.

Cheers

-----------------
Aaron Morton
Freelance Cassandra Developer
@aaronmorton
http://www.thelastpickle.com

On 22 Jul 2011, at 19:05, Eldad Yamin wrote:

> In order order to split the nodes.
> SimpleGeo have max 1,000 recods (i.e places) on each node in the tree, if the number
is >1,000 they split the node.
> In order to avoid that more then 1 process will edit/split the node - transaction is
needed.
> 
> On Jul 22, 2011 1:01 AM, "aaron morton" <aaron@thelastpickle.com> wrote:
> >> But how will you be able to maintain it while it evolves and new data is added
without transactions?
> > 
> > What is the situation you think you need transactions for ?
> > 
> > Cheers
> > 
> > -----------------
> > Aaron Morton
> > Freelance Cassandra Developer
> > @aaronmorton
> > http://www.thelastpickle.com
> > 
> > On 22 Jul 2011, at 00:06, Eldad Yamin wrote:
> > 
> >> Aaron,
> >> Nested set is exactly what I had in mind.
> >> But how will you be able to maintain it while it evolves and new data is added
without transactions?
> >> 
> >> Thanks!
> >> 
> >> On Thu, Jul 21, 2011 at 1:44 AM, aaron morton <aaron@thelastpickle.com>
wrote:
> >> Just throwing out a (half baked) idea, perhaps the Nested Set Model of trees
would work http://en.wikipedia.org/wiki/Nested_set_model
> >> 
> >> * Ever row would represent a set with a left and right encoded into the key
> >> * Members are inserted as columns into *every* set / row they are a member.
So we are de-normalising and trading space for time. 
> >> * May need to maintain a custom secondary index of the materialised sets. e.g.
slice a row to get the first column >= the left value you are interested in, that is the
key for the set. 
> >> 
> >> I've not thought it through much further than that, a lot would depend on your
data. The top sets may get very big, . 
> >> 
> >> Cheers
> >> 
> >> -----------------
> >> Aaron Morton
> >> Freelance Cassandra Developer
> >> @aaronmorton
> >> http://www.thelastpickle.com
> >> 
> >> On 21 Jul 2011, at 08:33, Jeffrey Kesselman wrote:
> >> 
> >>> Im not sure if I have an answer for you, anyway, but I'm curious....
> >>> 
> >>> A b-tree and a binary tree are not the same thing. A binary tree is a basic
fundamental data structure, A b-tree is an approach to storing and indexing data on disc for
a database.
> >>> 
> >>> Which do you mean?
> >>> 
> >>> On Wed, Jul 20, 2011 at 4:30 PM, Eldad Yamin <eldad87@gmail.com> wrote:
> >>> Hello,
> >>> Is there any good way of storing a binary-tree in Cassandra?
> >>> I wonder if someone already implement something like that and how accomplished
that without transaction supports (while the tree keep evolving)?
> >>> 
> >>> I'm asking that becouse I want to save geospatial-data, and SimpleGeo did
it using b-tree:
> >>> http://www.readwriteweb.com/cloud/2011/02/video-simplegeo-cassandra.php
> >>> 
> >>> Thanks!
> >>> 
> >>> 
> >>> 
> >>> -- 
> >>> It's always darkest just before you are eaten by a grue.
> >> 
> >> 
> > 


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