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Learning SQLite for iOS

You're reading from  Learning SQLite for iOS

Product type Book
Published in Mar 2016
Publisher
ISBN-13 9781785288975
Pages 154 pages
Edition 1st Edition
Languages
Author (1):
Gene Da Rocha Gene Da Rocha
Profile icon Gene Da Rocha
Toc

Table of Contents (15) Chapters close

Learning SQLite for iOS
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
1. Introduction to SQL and SQLite 2. Database Design Concepts 3. Administering the Database 4. Essentials of SQL 5. Exposing the C API 6. Using Swift with iOS and SQLite 7. iOS Development with PhoneGap and HTML5 8. More Features and Advances in SQLite Index

Database locking and deadlocks


A deadlock occurs when one or many actions or SQL statements compete for data access and table updates or manipulation at the same time as another process or action. Since it works with a transaction, one process can't move forward or complete because the other process or action holds, and is waiting for a resource, hence a deadlock.

So, in a database, records of process one would attempt to update, but process two would like to update some of the same rows, or a conflict of another table in which the transaction occurs. Some form of data locking mechanism to manage and reduce conflict must happen. Code around the transaction can be added with a retry indicator of three, for example, so if there is a deadlock, it will retry, and after the third attempt, it would roll back or give the user an opportunity to retry.

Deadlocking is a common occurrence in multithreaded and multiprocessing operating systems, which are performing a variety of tasks and attempting to...

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