[Data-modeling] underlying graph database

[Scott Meyer]

Can Altineller wrote:
> Hello,
> 
> I had read a blog post saying not to pay any attention to the underlying
> graph database that freebase uses - but I am curious.
> What kind of representation of a graph freebase uses, and how is it
> persisted? Does freebase use a database, or an oodbms or a lucene index?

We have written our own graph database on top of Unix.  We don't
have an RDBMS or OODB storage layer because conventional databases
don't handle the volume  of self-joins that graph queries generate.
Persistence is via memory mapped files with our own transaction
manager, custom tailored to provide exactly the (minimal) ACID
requirements that we have.

We do use Lucene for our search engine; it is currently
completely separate from our graph store.

Please pay no attention to the underlying graph database.
Go on about your business.  Nothing to see here.  :-)

-Scott