"COMPACT STORAGE imposes the limit that you can't add columns to your tables."
Is absolutely false. If anything CQL is imposing the limits!
Simple to prove. Try something like this:
create table abc (x int);
insert into abc (y) values (5);
and watch CQL reject the insert saying something to the effect of 'y? whats that? Did you mean CQL2 OR 1.5?, or hamburgers'
Then go to the Cassandra cli and do this:
create column family abd;
set ['abd']['y']= '5';
AND IT WORKS!
I noticed the nomenclature starting to spring up around the term "legacy tables" and docs based around "can't do with them". Frankly it makes me nuts because...
This little known web company named google produced a white paper about what a ColumnFamily data model could do http://en.wikipedia.org/wiki/BigTable
. Cassandra was build on the BigTable/ColumnFamily data model. There was also this big movement called NoSQL, where people wanted to break free of query languages and rigid schema's....