BTW my request could be somehow related to this post (but it's much more generic) https://bitcointalk.org/index.php?topic=267618.0
If you are looking for this kind of information you could just use/build a parser for all unspent transactions. I also made a parser myself which parses all used addresses (420 Million plus at the moment). But this is all done by using a traditional relational database since I'm not fully aware what a graph database is 
Interesting, can you share some details?
Have you used a RDBMS like MySQL or similar?
Have you had any issues importing the blockchain in the DB?
What did you do it for? Did you discover something interesting?
Please share.