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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
Languages
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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

Deleting columns

Upon further consideration, we may decide that location is a better column name than city_state. Cassandra does not allow us to rename existing data columns; however, since we haven't put any data in the city_state column yet, we can achieve our goals simply by dropping the city_state column and adding a location column instead:

ALTER TABLE "users" DROP "city_state"; 
ALTER TABLE "users" ADD "location" text;

The DROP command within the ALTER TABLE statement looks just like the ADD command, except that we need not specify the column's type—only its name is sufficient. Looking at the output of DESCRIBE again, we've now got the columns set up the way we'd like:

Before we proceed with table operations, let's change the email of user alice to maintain similarity. Remember, we changed the email earlier in Chapter 2, The First Table...

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