I built a member based analytics system. This system is growing rapidly and I have several tables that are approaching a gig in size.
We can only imagine what a "member based analytics system" is but a gig of data for a relatively new system is a little worrying. Can you give any info on what it is you're storing? Why is it growing so rapidly? is it because you're getting too many members or is their an issue with the design? Perhaps:
you're storing too much data - (a gig of growth for a new system is a lot)
you're not cleaning old data?
you should charge by usage and then the amount of data being stored will reduce?
if you envisage many more users (and a lot more growth) then the system should be installed on the client side rather than on a server?
Splitting tables is usually a bad idea and nearly always results in poorer overall system performance and way more maintenance issues.