Oracle can store as much data as you can throw at it. Really. Oracle is scalable to the petabyte level and as long as hardware platforms keep increasing processing capacity, memory, storage, and network throughput, that number will continue to get larger and larger. The difference between Oracle9i (i = internet) and Oracle10g (g = grid), is that Oracle added many new database administration and development features/functionality to Oracle10g with a renewed focus on grid (clustered) database performance and functionality and added many online database administration functions to allow databases to remain up while being maintained. Oracle11g, which has been out for many years and should be used over 9i or 10g, automated many database administration functions and extended business intelligence and data warehousing functionality. Oracle 12c (c = cloud) is on the way with many new features soon to be announced too.