Tuesday 18th November, 2014
9:00am to 10:00am
Gray and Reuter define consistency as: “A transaction is a correct transformation of the state. The actions taken as a group do not violate any of the integrity constraints associated with the state. This requires that the transaction be a correct program.”
Loosely translated, you should be happy with yourself. In your own opinion, you should be sane.
Through the years, this most ill defined property of the ACID transaction has been conflated with isolation and interpreted through the prism of read/write updates to an apparently centralized record oriented database. This suits systems developers that need a narrow definition to feel they can accomplish something. Unfortunately, it leaves many real world problems in the dust.
In this talk, we will explore the models of consistency and the facades of reality used in practical systems.
Salesforce software archtiect
Pat Helland has 36 years experience implementing databases, transaction systems, application platforms, replication systems, fault tolerance, and distributed systems.
During the 1980s, Pat was Chief Architect of the Tandem NonStop's TMF (Transaction Monitoring Facility), the transaction processing and recover engine behind NonStop SQL.
He started working at Microsoft in 1994 and drove the design and architecture for MTS (Microsoft Transaction Server), the N-tier transactional computing environment for Windows as well DTC, the Distributed Transaction Coordinator. A few years later, Pat led the development of SQL Service Broker, a high speed exactly once transactional messaging system.
From 2005 to early 2007, Pat worked at Amazon on the Product Catalog. In 2007, he returned to Microsoft working on a number of projects including adding indexing and affinitized placement of data into Cosmos, the massively parallel computation and storage engine behind Bing (Big Data). Cosmos supports exabytes of data running on hundreds of thousands of computers. He was one of the original architects for the realtime event driven transactional engine for Cosmos.
Since early 2012, Pat has worked at Salesforce.com on database management, storage, and data center issues.
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