You may want to look at using virtual keyspaces:
http://hector-client.github.io/hector/build/html/content/virtual_keyspaces.html

And follow these tickets:
http://wiki.apache.org/cassandra/MultiTenant

-brian


On May 6, 2013, at 2:37 AM, Darren Smythe wrote:

How many keyspaces can you reasonably have? We have around 500 customers and expect that to double end of year. We're looking into C* and wondering if it makes sense for a separate KS per customer?

If we have 1000 customers, so one KS per customer is 1000 keyspaces. Is that something C* can handle efficiently? Each customer has about 10 GB of data (not taking replication into account).

Or is this symptomatic of a bad design?

I guess the same question applies to our notion of breaking up the column families into time ranges. We're naively trying to avoid having few large CFs/KSs. Is/should that be a concern?

What are the tradeoffs of a smaller number of heavyweight KS/CFs vs. manually sharding the data into more granular KSs/CFs?

Thanks for any info.

-- 
Brian ONeill
Lead Architect, Health Market Science (http://healthmarketscience.com)
mobile:215.588.6024
blog: http://weblogs.java.net/blog/boneill42/
blog: http://brianoneill.blogspot.com/