Database Reference
In-Depth Information
Summary
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" opera-
tion. We explored situations in which upserts can produce undesirable behavior, particu-
larly 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 condi-
tional updates, as a way to mutate Cassandra data with some of the data integrity guaran-
tees 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 multiple values within a
single column.
