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Learning Apache Cassandra

By : Brown

4.4 (13)

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.

Preface

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Free Chapter

1. Getting Up and Running with Cassandra

1. Getting Up and Running with Cassandra

What Cassandra offers, and what it doesn't

Installing Cassandra

Bootstrapping the project

Creating a keyspace

Summary

2. The First Table

2. The First Table

Creating the users table

Inserting data

Selecting data

Developing a mental model for Cassandra

Summary

3. Organizing Related Data

3. Organizing Related Data

A table for status updates

Working with status updates

Anatomy of a compound primary key

Beyond two columns

Compound keys represent parent-child relationships

Coupling parents and children using static columns

Refining our mental model

Summary

4. Beyond Key-Value Lookup

4. Beyond Key-Value Lookup

Looking up rows by partition

Retrieving status updates for a specific time range

Paginating over rows in a partition

Reversing the order of rows

Paginating over multiple partitions

Building an autocomplete function

Summary

5. Establishing Relationships

5. Establishing Relationships

Modeling follow relationships

Storing follow relationships

Looking up follow relationships

Unfollowing users

Using secondary indexes to avoid denormalization

Summary

6. Denormalizing Data for Maximum Performance

6. Denormalizing Data for Maximum Performance

A normalized approach

Partial denormalization

Fully denormalizing the home timeline

Write complexity and data integrity

Summary

7. Expanding Your Data Model

7. Expanding Your Data Model

Viewing a table schema in cqlsh

Adding columns to tables

Deleting columns

Updating the existing rows

Removing a value from a column

Inserts, updates, and upserts

Lightweight transactions have a cost

Summary

8. Collections, Tuples, and User-defined Types

8. Collections, Tuples, and User-defined Types

The problem with concurrent updates

Collection columns and concurrent updates

Using lists for ordered, nonunique values

Using maps to store key-value pairs

Collections in inserts

Collections and secondary indexes

The limitations of collections

Working with tuples

User-defined types

Choosing between tuples and user-defined types

Comparing data structures

Summary

9. Aggregating Time-Series Data

9. Aggregating Time-Series Data

Recording discrete analytics observations

Recording aggregate analytics observations

Recording analytics observations

Summary

10. How Cassandra Distributes Data

10. How Cassandra Distributes Data

Data distribution in Cassandra

Data replication in Cassandra

Consistency

Handling conflicting data

Distributed deletion

Summary

A. Peeking Under the Hood

A. Peeking Under the Hood

Using cassandra-cli

The structure of a simple primary key table

Compound primary keys in column families

Collection columns in column families

Summary

B. Authentication and Authorization

B. Authentication and Authorization

Enabling authentication and authorization

Setting up a user

Controlling access

Authorization in action

Security beyond authentication and authorization

Summary

Wrapping up

Index

Index

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Paginating over rows in a partition

As our users create more and more status updates, we'll build pagination functionality into MyStatus so that the information on the page doesn't overwhelm readers. For the sake of convenience, let's say that each page will only contain three status updates.

To retrieve the first page, we'll use the LIMIT keyword that we first encountered in Chapter 2, The First Table:

SELECT "id", DATEOF("id"), "body"
FROM "user_status_updates"
WHERE "username" = 'alice'
LIMIT 3;

As expected, Cassandra will give us the first three rows in ascending order of id:

Paginating over rows in a partition

Now, we'll ask for the collection of rows where the id value is strictly greater than the last id we saw:

SELECT "id", DATEOF("id"), "body"
FROM "user_status_updates"
WHERE "username" = 'alice'
  AND id > 3f9df710-e8f7-11e3-9211-5f98e903bf02
LIMIT 3;

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