Subject Re: [Firebird-Architect] If Eventual Consistency Seems Hard, Wait Till You Try MVCC
Author James Starkey
That discussion makes a very common mistake about the relationship between consistency and serializability.  Academic folklore holds that the terms are synomymous.  They aren't, unless you are using two phase record locking.

Serializability is certainly a sufficient condition for consistency, but it isn't a necessary one.  Consistency can be defined as a set of constraints.  As long as the constraints are enforced, the database is, by definition, consistent.

The conflation of consistency and serializability is deeply routed in academic computer science.  It originated with the invention of record locking and IS necessary for record locking to produce consistent results.  For other consistency technologies, especially MVCC, it is neither necessary nor desireable.

On Monday, May 25, 2015, mapopa@... [Firebird-Architect] <> wrote:

Jim Starkey