Appendix 2The CAP Theorem
Understanding the five database genres is an important selection criterion, but it’s not the only one. Another recurring theme in this book is the CAP theorem, which lays bare an unsettling truth about how distributed database systems behave in the face of network instability.
CAP proves that you can create a distributed database that is consistent (writes are atomic and all subsequent requests retrieve the new value), available (the database will always return a value as long as a single server is running), or partition tolerant (the system will still function even if server communication is temporarily lost—that is, a network partition), but you can have only two at once.
In other words, you can create a distributed ...
Get Seven Databases in Seven Weeks now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
