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From Eldad Yamin <elda...@gmail.com>
Subject Re: b-tree
Date Fri, 22 Jul 2011 07:05:10 GMT
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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