Book Image

Apache Cassandra Essentials

By : Nitin Padalia
Book Image

Apache Cassandra Essentials

By: Nitin Padalia

Overview of this book

Apache Cassandra Essentials takes you step-by-step from from the basics of installation to advanced installation options and database design techniques. It gives you all the information you need to effectively design a well distributed and high performance database. You’ll get to know about the steps that are performed by a Cassandra node when you execute a read/write query, which is essential to properly maintain of a Cassandra cluster and to debug any issues. Next, you’ll discover how to integrate a Cassandra driver in your applications and perform read/write operations. Finally, you’ll learn about the various tools provided by Cassandra for serviceability aspects such as logging, metrics, backup, and recovery.
Table of Contents (14 chapters)
Apache Cassandra Essentials
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Delete operations


In Cassandra, a delete operation does not delete the requested data immediately. Instead, it puts a marker over the deleted data. This marker is called a tombstone. A tombstone's age is defined by per-column family option gc_grace_seconds. After gc_grace_seconds has passed, Cassandra clears data marked with tombstones, and it clears all tombstones during the compaction of the column family.

Tip

If a node is down for loger than the time specified by gc_grace_seconds and is recovered, there is a chance that the deleted data will come back. To avoid such scenarios, nodes dead for such a long time should be replaced instead of being added back to the cluster.