In this chapter, we added several new tools to our arsenal of Cassandra knowledge. You now know how to add and remove columns from existing tables in our database schema, and we explored the UPDATE query. You learned that CQL's INSERT and UPDATE have behavior that's quite surprising to those who are accustomed to the equivalent operations in SQL, and that in reality both queries in CQL are performing an underlying "upsert" operation. We explored situations in which upserts can produce undesirable behavior, particularly in situations where there is concurrent access to the same resource by multiple actors. Also, we introduced lightweight transactions in the form of conditional inserts and conditional updates, as a way to mutate Cassandra data with some of the data integrity guarantees that we are used to having in relational databases.

In the next chapter, we will undertake an exploration of data structures within individual columns, exploring several different ways to store and manipulate...