Storing Terrain Data using RavenDB and Photon

I am new to database programming, and researching on storing terrain data to be used by a mmo/game server to access terrain information to make an authoritative approach possible. I am using Photon for server and learning RavenDB to store vertex info.(i am new to db programming)

As a demo, I have 500 x 500 terrain and stored all vertex info into the database(2.5mil vertices) with

id = x.toString("D4") + y.toString("D4")

so that i can load using the same technique. loading a single vertex takes a long time using a querying approach. i am certain my approach isnt right, is there anyone can show me the right path? or is there any better approach to solve this problem?

Or should I split the database into segments for each cells i.e 50x50 into one database another 50x50 into one?

thank you!