On 4/27/2010 20:28, Larry Sheldon wrote:
On 4/27/2010 20:25, Richard Barnes wrote:
<off-topic> <IANADBExpert>
Interesting theory, but seems kind of wrong. Wouldn't the time to look up or fail be tied to the complexity of how the key space is populated? In any case, it seems like the time to succeed or fail will usually be about the same, since you'll try to access the value for a key and either find something there or fail.
The theory is based on the notion that if you find something you stop looking for it. If what you are looking for is not there, you have to search all of the key-space, regardless of the index method.
That is why, when I was actively designing (or supervising the design) of data-bases, we tried to make the most likely hits at the beginning of the key-space. In general, easier to say than to do. And not as intuitive as you might think. (In the old days, there was the closely related entertainment of predicting which benefited most from cached-disc systems, random files or sequential files.) -- Somebody should have said: A democracy is two wolves and a lamb voting on what to have for dinner. Freedom under a constitutional republic is a well armed lamb contesting the vote. Requiescas in pace o email Ex turpi causa non oritur actio Eppure si rinfresca ICBM Targeting Information: http://tinyurl.com/4sqczs http://tinyurl.com/7tp8ml