Archive for January, 2007

Dr. Jim Gray

January 31, 2007

I have always been inspired by Dr. Jim Gray’s publications and talks.

I first learned about his famous book called "Transaction Processing: Concepts and Techniques" at a DB Expo in San Francisco in 1995. I never took the time to read it but its everything you ever needed to know about database transactions packed into 1,100 small fonted pages. At the time, I worked with some IBM CICS developers from Hursley, England that worshipped the book.

My first chance to see him speak was at a Microsoft PDC in 1997. He gave a talk on Scalable Computing. Ever since, I’ve been a groupee.

He deserves much credit for Microsoft’s scalability efforts. It’s built on the idea that a large amount of little parts are much better than a few big parts. So if 100 Terabytes of disk space is needed then it’s better to use 10,000 : 10 GB disk drives than 100 : 1,000 GB (1TB) disk drives. If you do the math, the cost is lower, performance is higher and is more reliable.

His famous 5 Minute Rule:

"In Psychology, the answer is always 5±2. In Physics, the answer is always transcendental. In Digital computing, the answer is always a multiple of 5 — for example, how many fingers and toes do you have? In all fields, the problem is to find the question.

One interesting question is: When does it make economic sense to make a piece of data resident in main memory and when does it make sense to have it resident in secondary memory (disc) where it must be moved to main memory prior to reading or writing?

5 Minute Rule: Pages referenced every five minutes should be memory resident."

The sads news is that on Sunday (1/28), Dr. Jim Gray was reported missing at sea.

If interested, there are great video interviews of Dr. Jim Gray here and here.


Photo that I took of Dr. Jim Gray 16 months prior to the tragedy while at Microsoft’s PDC 2005 event.