Learning Apache Cassandra - Second Edition

Nested collections

Suppose that we wish store a set of phone numbers for a user each identified by a category of phone type, such as home phone or office phone. We can do this by using a map where the key is phone type and value can be a set of phone numbers, assuming there are multiple phone numbers of each type. This is an example of nested collection where we are using a set as value within a map. Let us try to create the collection:

ALTER TABLE "users" ADD "telephone_numbers" map<text, set<text>>;

You will get an error saying non-frozen collections are not allowed inside collections:

Cassandra lets us use nested collection types only ...