How to optimal using column family?

[Andrzej]

I need database to store transactions. Each transaction can have many 
inputs and outputs, usually 1-3 but sometimes about 100.
Previously in sql I have two main tables: first table had one row per 
transaction and store common transaction things; second had one row per 
one input/output.
But now are column families. I need two tables or family input and 
output and many columns like input:col57, output:col26 ? Which is better 
efficient?