Cassandra Data Modeling - Beginning Apache Cassandra Development - page 43

Figure 2-10 . Followers for ritaf, jhassell, and imvivek have been added

5. We can update the collection to delete an element as follows. Figure

2-10 shows the result:

update users set followers = followers -
{'guestuser'} where twitter_id = 'imvivek';

Figure 2-11. Updated set of followers after removing guestuser for imvivek

Collection support can be a good alternative for achieving Adding dynamic
columns over Cassandra. Composite key is a combination of multiple table fields
where the first part is referred to as partition key and the remaining part of the com-
posite key is known as cluster key. Chapter 3 will discuss achieving dynamic columns
using composite columns.

Secondary Indexes

In a distributed cluster, data for a column family is distributed across multiple nodes,
based on replication factor and partitioning schema. However data for a given row key
value will always be on the same node. Using the primary index (e.g., Row key) we
can always retrieve a row. But what about retrieving it using non-row key values?