giraph-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Claudio Martella <claudio.marte...@gmail.com>
Subject Re: Information
Date Wed, 26 Mar 2014 15:30:46 GMT
Nope, you can think about Giraph as MapReduce for graphs. Probably neo4j &
C is the way to go for you.


On Wed, Mar 26, 2014 at 3:18 PM, Angelo Immediata <angeloimm@gmail.com>wrote:

> hi Sebastian
>
> OK...I got it....I was thinking I could use it for an online scenario......
> Thank you
>
> Angelo
>
>
> 2014-03-26 14:52 GMT+01:00 Sebastian Schelter <ssc@apache.org>:
>
> Hi Angelo,
>>
>> It very much depends on your use case. Do you want to precompute paths
>> offline in batch or are you looking for a system that answers online?
>> Giraph has been built for the first scenario.
>>
>> --sebastian
>>
>>
>> On 03/26/2014 02:48 PM, Angelo Immediata wrote:
>>
>>> 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
>>>>
>>>>
>>>>
>>>
>>
>


-- 
   Claudio Martella

Mime
View raw message