code: public void initCf(UUID cfId, String cfName, boolean loadSSTables)
      {
          ColumnFamilyStore cfs = columnFamilyStores.get(cfId);
  
          if (cfs == null)
          {
              // CFS being created for the first time, either on server startup or new CF being added.
              // We don't worry about races here; startup is safe, and adding multiple idential CFs
              // simultaneously is a "don't do that" scenario.
              ColumnFamilyStore oldCfs = columnFamilyStores.putIfAbsent(cfId, ColumnFamilyStore.createColumnFamilyStore(this, cfName, loadSSTables));
              // CFS mbean instantiation will error out before we hit this, but in case that changes...
              if (oldCfs != null)
                  throw new IllegalStateException("added multiple mappings for cf id " + cfId);
          }
          else
          {
              // re-initializing an existing CF.  This will happen if you cleared the schema
              // on this node and it's getting repopulated from the rest of the cluster.
              assert cfs.name.equals(cfName);
              cfs.metadata.reload();
              cfs.reload();
          }
      }
docs: adds a cf to internal structures, ends up creating disk files).