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Learning Apache Cassandra

Learning Apache Cassandra

By : Brown
4.4 (13)
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Learning Apache Cassandra

Learning Apache Cassandra

4.4 (13)
By: Brown

Overview of this book

If you're an application developer familiar with SQL databases such as MySQL or Postgres, and you want to explore distributed databases such as Cassandra, this is the perfect guide for you. Even if you've never worked with a distributed database before, Cassandra's intuitive programming interface coupled with the step-by-step examples in this book will have you building highly scalable persistence layers for your applications in no time.
Table of Contents (14 chapters)
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13
Index

The limitations of collections


As we saw, collection columns are a useful and versatile feature of CQL. In fact, we might suppose that collections would be a good way to model data we've modeled in other ways in previous chapters. For instance, why not model a user's status updates as a list of text values in the users table?

As it turns out, collection columns do have some limitations that circumscribe the cases in which they're the best solution. We'll explore the major limitations now.

Reading discrete values from collections

The most powerful feature of CQL collections is the ability to write discrete values to a collection. It's possible to append a single value to a list, update a single key-value pair in a map, remove a specific value from a set, and so on.

At read time, however, there is no special support for reading discrete values. For instance, we might want to be able to do something like the following to read a specific element from a list column:

SELECT "shared_by"[2]
FROM "user_status_updates...

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