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Learning Apache Cassandra

You're reading from   Learning Apache Cassandra Managing fault-tolerant, scalable data with high performance

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Product type Paperback
Published in Apr 2017
Publisher
ISBN-13 9781787127296
Length 360 pages
Edition 2nd Edition
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Author (1):
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Sandeep Yarabarla Sandeep Yarabarla
Author Profile Icon Sandeep Yarabarla
Sandeep Yarabarla
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Table of Contents (15) Chapters Close

Preface 1. Getting Up and Running with Cassandra FREE CHAPTER 2. The First Table 3. Organizing Related Data 4. Beyond Key-Value Lookup 5. Establishing Relationships 6. Denormalizing Data for Maximum Performance 7. Expanding Your Data Model 8. Collections, Tuples, and User-Defined Types 9. Aggregating Time-Series Data 10. How Cassandra Distributes Data 11. Cassandra Multi-Node Cluster 12. Application Development Using the Java Driver 13. Peeking under the Hood 14. Authentication and Authorization

Adding columns to tables

Let's say we want to allow our users to enter their location in the profile. To store a user's location, we need a new column in the users table; fortunately, it's perfectly straightforward to add a new column to an existing table:

ALTER TABLE "users" ADD "city_state" text; 

This query instructs Cassandra that we'd like to add a column named city_state, of type text, to the users table. It's identical to the equivalent operation in SQL, although the CQL ALTER TABLE statement is much more constrained in the operations it can perform.

Now let's check our table schema again:

DESC TABLE "users";

Here, we have used the command DESC, which is a short version of the DESCRIBE command. As we hoped, we've got a city_state column in the schema. I've omitted the table properties for brevity:

...
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