e-commerce. Every time we use an ATM, reserve a seat on an airplane, or purchase an item on the Web, we are relying on the mechanisms Jim first developed 30-odd years ago. These techniques ensure that the “right” thing always happens—even in the presence of software and hardware failure. While they seem second-nature to us today, when Jim conceived them

 

they required very deep insight into the complexities of concurrently executing queries and updates against a shared database system.

Later in his career, Jim became interested in helping natural scientists with their work. He pioneered putting astronomy observation data into a database system. In this way scientists could query their data in SQL, rather than having to write custom programs in C++ or some other general-purpose language. Implementation of this idea for the Sloan Digital Sky Survey (www. sdss.org/) has resulted in more than 2,000 astronomy publications based on querying this data set through SQL.

Jim received his bachelor’s and Ph. D. degrees from the University of California, Berkeley, in 1966 and 1969, respec-

tively. Soon after receiving his Ph.D. he joined the IBM San Jose Research Laboratory (now known as the IBM Almaden Research Center) where he helped lead the design and development of System R, one of the first database systems to use the relational data model. In 1988, System R (along with INGRES, for the INteractive Graphics REtrieval System, project at Berkeley) was honored with the ACM Software Systems Award for pioneering development of relational database systems. It was as part of the System R project that Jim first developed the notion of what it means for transactions to be “serializable”; that is, they produce the same outcome as the serial ordering of the transactions. He also developed the connection between serializability and database consistency and how a simple protocol known as

“two-phase locking” could be used t o ensure that two or more transactions are serializable with respect to each other without the user having to understand the semantics of the transactions.

From the time he left IBM in 1980 to his joining Microsoft in 1995, Jim worked for Tandem Computers (1980–1990) on the parallel relational database system Non-Stop SQL and at Digital Equipment Corporation (1990–1995). Over the course of his career Jim also made numerous technical contributions beyond his work on transactions, including database system architectures and algorithms, fault tolerance, input/output architectures, parallel database systems, database system performance evaluation and benchmarking, multidimensional data analysis, and e-science, including the TerraServer (www.terraserver-usa. com) and the Sloan Digital Sky Survey project. When he disappeared at sea in 2007, he held the title of Technical Fel-

low at Microsoft.

That disappearance spurred the computer science community to action, and a massive amateur search effort was pulled together to augment the professional one launched by the U. S. Coast Guard. This effort entailed retargeting satellites to sweep the region of interest and posting the imagery on the Amazon Mechanical Turk site ( www.mturk.com) so the distributed community could examine it in parallel to look for his sailboat, Tenacious. Possible sightings were then examined by experts in image rec-

ognition. It is the hope of the community that this imagery workflow will be automated and performed in real time during future searches. Parallel efforts searched for wreckage along the entire length of the California coastline and posted flyers at every marina in California. No trace of Jim’s boat was ever found. An extensive underwater search was equally unsuccessful. Hence, it is

 

likely that we will never know what happened to Tenacious, and the loss of Jim Gray will remain a mystery.

I (Michael) first met Jim while I was a struggling assistant professor at Berkeley in 1971. He was instrumental in helping me do the research that led to my first publication, which dealt with a simplification of Jay Forrester’s model of an urban area. I am forever grateful for his help motivating me in the publish-or-perish world of an assistant professor.

Jim was obviously brilliant, as anyone who talked to him quickly realized. However, he also read widely and knew a lot about a lot of things. In fact, he is one of the few people I have found to be intellectually intimidating. Moreover, he was always willing to read papers that other researchers sent him and