I know it's an old topic, but I want to see if anything's changed on the number of column families that C* supports, either in 1.2.x or 2.x.
For a number of reasons , we'd like to support multi-tenancy via separate column families. The "problem" is that there are around 5,000 tenants to support and each one needs a small handful of column families each.
The last I heard C* supports 'a couple of hundred' column families before things start to bog down.
What will it take for C* to support 50,000 column families?
I'm about to dive into the code and run some tests, but I was curious about how to quantify the overhead of a column family. Is the reason performance? Memory? Does the off-heap work help here?
 The main three reasons:
- ability to wholesale drop data for a given tenant via drop keyspace/drop CFs
- ability to have divergent schema for each tenant (partially effected by DSE Solr integration)
- secondary indexes per tenant (given requirement #2)