Archive for February, 2007

Inaugural Edition of Carnival of Mathematics out &= I am in it!

Monday, February 12th, 2007

Carnival of Mathematics 

The Inaugural Edition of the first and only Carnival of Mathematics has been published at Abstract Nonsense, and my entry on spigot algorithms is in it!  Most of the comments are about a probability “paradox” with similarities to the Monty Hall problem.  But my favorite entry tells a famous John Von Neumann story (note, the Magyar stamp leaves out the Von).


Jim Gray = Database Genius

Friday, February 2nd, 2007

Jim - It's big


I am very saddened to hear that noted database genius, and friend, Jim Gray appears to be lost at sea.  He was out alone in a sailboat scattering his mother’s ashes.  She died last year at 97.

I knew Jim mostly through my work at the TPC where we convinced each other that his notion of ACID properties defining a database system could be worked into a standard specification (he didn’t think so – I did).  Jim not only laid the foundation for all of today’s database systems, he was exceptionally generous in sharing his research with others.

One very small example of his work is the 5-minute rule, essentially a rule-of-thumb stating when you should trade off disk storage with RAM, viz., if you access the data again in less than 5-minutes.  The derivation has a technological and economic component.

5-minute rule

In 2002, when Jim proposed this now-famous rule, the numbers worked out to ~356 seconds, which Jim wisely rounded to 5 minutes.  Today, AcessPerSecondPerDisk has doubled, PricePerDiskDrive has dropped by a factor of 10 (note: it doesn’t matter that disk sizes have increased – a different topic that Jim discusses as the Problem of the TerrorByte!), and PricePerMBof DRAM has dropped by a third.  So the 5-minute rule is today the 53-second rule, or, as Jim would more wisely call it, the 1-minute rule.

Updates:  Microsoft update site, Coast Guard report site, and personal search site.

Update [2/6/2007]: Public website up ( ) with MISSING posters and how to help search.  Here is Sunday’s NPR story on Jim.  Istvan Csabai found a green sailor’s dye marker off the coast of Los Angeles.

P.S. A tribute to James (“Jim”) Nicholas Gray (born 1944).

Update [7/24/2007]: Wired magazine publishes an article on Jim and the search titled Inside the High Tech Hunt for a Missing Silicon Valley Legend.