Hello Luca,

60M of nodes and 400M of edges is not that big, you could manage the entire
> graph in 1 machine, but depends by the kind of operation you do against the
> graph:
>
>    - is it mostly read than write?
>
>
Yes. The database is write-once, but reads follow unpredictable patterns.

>
>    - what kind of traversal you will do?
>
> The main operation will be a shortest-path between any two vertices.
The number of hops between any two vertices follow a scale-free
distribution.

>
>    - what's the expected performance in terms of query/sec?
>
> I don't need to comply to a particularly stringent SLA, but it has to be
fast...
For instance: internally, does OrientDB  memoize traversal results ?

[2] - http://en.wikipedia.org/wiki/Memoization

 Can OrientDB automatically shard (via some kind of semi/automatic
>> graph-clustering) a large graph across
>> a set of OrientDB nodes ?
>>
>
> You can shard the graph against multiple nodes. We have 3 strategies to
> distribute data against different machines (round-robin, balanced and
> sticky), but 99% of the times it's better to rely to the application where
> to store the nodes because he better know the domain.
>

Can you point me to the documentation where these 3 strategies are
described, if any ?


>  How the nodes communicate to each other ?
>>
>
> All nodes are connected via TCP/IP, so the traversal is transparent, but
> could be costly if you have many hop back and forth on machines.
>

Are connections established once and for all, or they are created on the
fly only when a given edge is traversed, and closed once the traversal has
completed ?
If the vertices are sharded following a min-cut clustering, this cost
should be low...right?


>  Is there some rebalancing mechanism in the case a graph-cluster becomes
>> too big ?
>>
>
> With 2.0 we have a "move vertex" command to move vertices to nodes, this
> is very useful to move one node or entire clusters.
>

Interesting. Given latest version I see is 1.7.8, the question is due: when
do you plan to release 2.0 ?


>
>> 1 -
>> http://www.odbms.org/wp-content/uploads/2014/05/an-empirical-comparison-of-graph-databases.pdf
>>
>
> This is a pretty old benchmark with the old version of OrientDB that used
> local and mvrb+tree indexes. Now OrientDB is totally different, and it
> scales much better.
>

I understand your concerns. But the paper is not so old after all,
officially published back in September 2013 here:
http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6693403&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D6693403


>  By the way I asked to the authors of the paper to retry the very same
> benchmark against 1.7.x but they never responded me...
>

Too bad :-(

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