Isolation Concepts (Chp 7: Transaction processing book)
Continuing with our Transaction book reading , this week we look at the first part of the Isolation concepts. The book gets conceptual to provide the theory behind isolation of transactions. Finally we are getting some protocol action. The first part of the chapter covers the following: Introduction to Isolation, The Dependency Model of Isolation (Three Bad Dependencies), Isolation: The Application Programmer’s View, and Isolation Theorems. A couple things immediately pop out. Chapter 7 equates Serializability (SER) with Isolation, whereas today snapshot isolation (SI) is the most popular isolation level, and we have a bunch of other weaker isolation levels . Secondly, Chapter 7 equates two-phase-locking (2PL) with the isolation implementation techniques, whereas today MVCC and OCC are also popular implementation techniques. Although optimistic concurrency control (OCC) was established by 1980, the book did not consider OCC mechanisms at all. This is normal, when we consider the