incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Mike Malone <m...@simplegeo.com>
Subject Re: b-tree
Date Fri, 22 Jul 2011 18:25:58 GMT
On Fri, Jul 22, 2011 at 12:05 AM, Eldad Yamin <eldad87@gmail.com> 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.
>
You don't need a transaction, you just need consensus and/or idempotence. In
this case both can be achieved fairly easily.

Mike


> 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.
> >>
> >>
> >
>

Mime
View raw message