Upgrading Cassandra and Troubleshooting - Beginning Apache Cassandra Development - page 285

name frozen <user_metadata>,

);

Here, name is a frozen type of user_metadata for the users table in the key-
space twitter_keyspace . With a column field defined with the frozen
keyword, Cassandra serializes multiple components in single value. For example, with
user_metadata , fname and lname will be serialized as a single value. Once a
user-defined data type is frozen with the frozen keyword, we cannot update compon-
ents of the user-defined type.

Indexing on Collection Attributes

In Chapter 2 we discussed data modeling concepts and working with collections. Also
under the “Secondary Indexes” section in Chapter 2 , we discussed that indexes over
Cassandra collection attributes were not supported. With Cassandra 2.1, we now can
create indexes over Cassandra collection attributes like this:

create table users(user_id text PRIMARY KEY,fullname
text,email text,password text, followers map<text, text>);
insert into
users(user_id,email,password,fullname,followers) values
('imvivek','[e-mail]','password','vivekm',{'mkundera':'milan
kundera','guest': 'guestuser'});

create index followers_idx on users(followers);

Here, users is a table and followers is a map containing user_id as its key
and name as the value. The create index command will enable an index over the
values of the followers map (e.g., full name). We can also enable indexes over fol-
lowers map keys (e.g., user_id ) like this:

create index followers_idx_keys on users(KEYS(followers));

We can fetch records from followers using indexes as follows:

SELECT email, followers FROM users WHERE followers
CONTAINS 'milan kundera';