I don't see this formally documented anywhere, so I thought I'd give a heads-up to folks using Pig with Cassandra.

In pre-1.2.10 versions, storing data into Cassandra required a query like this: 
STORE data INTO 'cql://keyspace/table?output_query=update table set some_value @ #' USING CqlStorage();

In 1.2.10, the expansion of the "@" and "#" characters has been removed, and the query is now expected to be URL encoded. The above query would become:
STORE data INTO 'cql://keyspace/table?output_query=update+table+set+some_value+%3D+%3F' USING CqlStorage();

I've also found that you can't store Pig ints into Cassandra bigints any more - you have to cast it to a long in your Pig script.

I've opened JIRAs for these issues: