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From Angelo Immediata <angelo...@gmail.com>
Subject Re: Information
Date Wed, 26 Mar 2014 13:48:01 GMT
hi Claudio

so, if I understood correctly, it has no sense to use Giraph for shortest
path calculation in my scenario

Am I right?


2014-03-26 13:27 GMT+01:00 Claudio Martella <claudio.martella@gmail.com>:

> It looks like you're expecting to use Giraph in an online fashion, such as
> you would use a database to answer queries within milliseconds or seconds.
> Giraph is an offline batch processing system.
>
>
> On Wed, Mar 26, 2014 at 11:11 AM, Angelo Immediata <angeloimm@gmail.com>wrote:
>
>> Hi there
>>
>> In my project I have to implement a routing system with good performance;
>> at the beginning this system should be able in giving routes information
>> only for one italian region (Lombardia) but it could be used for the whole
>> Italy (or world....)
>> Let's stop to the Lombardia for now. By reading OSM files I can create my
>> own graph in the best format i can use it; then I need to use Dijkstra (or
>> any other algorithm) in order to propose to the user K possible paths from
>> point A to point B (K becouse i need to show to the customer also the
>> alternatives). I can't use Contraction Herarchy algorithm becouse I need to
>> take care of external events that can modify the weights on my built graph
>> and this implies that I should create the "contracted" graph once again and
>> this can be a very onerous operation
>>
>> By my experimentations, I saw that by reading the Lombardia OSM file I
>> should create a graph with around 1 million of vertexes and 6 million of
>> edges and I was thinking to use Giraph to solve my issue (I saw this link
>> http://giraph.apache.org/intro.html where you talked about shortestpaths
>> problem
>> I have a couple of question for you giraph/hadoop gurus
>>
>>    - does it make sense to use giraph for my scenario?
>>    - must i respect some graph format to pass to the giraph algorithm in
>>    order to have K shortest paths from point A to point B? If so....which
>>    format should I respect?
>>    - what would be perfomance by using giraph? I know that Dijstra
>>    algorithm problem is that it is slow.....by using giraph will I be able in
>>    improving its performances on very large graph?
>>
>> I know these can seem very basic questions, but I'm pretty new to giraph
>> and I'm trying to understand it
>>
>> Thank you
>> Angelo
>>
>
>
>
> --
>    Claudio Martella
>
>

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