create column family testing
  with key_validation_class = 'SomeType1'
  and comparator = 'SomeType2'
  and default_validation_class = 'SomeType3'

在这条线上这些代表什么。

set testing[a][b] = c

我的观点正确吗？

a is of type SomeType1 
SomeType2 is how columns are sorted / sliced.
c is of type SomeType3

我的目标是创建一个存储来包含时间序列数据

testing[a][b] = c;
a is of type 'String' or 'UTF8Type'
b is 'LongType'
c is 'FloatType'

我应该能做到的

set testing['stats.randomNumber'][123456789] = 0.56;
set testing['stats.randomNumber'][123456790] = 90.33;