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Michael Stonebraker discusses the implications of
the CAP theorem on database management system applications
that span multiple processing sites.
michael Stonebraker “errors in Database Systems, eventual consistency, and the caP theorem” http://cacm.acm.org/ blogs/blog-cacm/83396 Recently, there has been considerable renewed interest in the CAP theorem1
for database management system
(DBMS) applications that span multiple processing sites. In brief, this theorem states that there are three interesting properties that could be desired by
C: Consistency. The goal is to allow multisite transactions to have the
familiar all-or-nothing semantics,
commonly supported by commercial
DBMSs. In addition, when replicas are
supported, one would want the replicas to always have consistent states.
A: Availability. The goal is to support a DBMS that is always up. In other
words, when a failure occurs, the system should keep going, switching over
to a replica, if required. This feature
was popularized by Tandem Computers more than 20 years ago.
P: Partition-tolerance. If there is a
network failure that splits the process-
ing nodes into two groups that cannot
talk to each other, then the goal would
be to allow processing to continue in