The following message is a courtesy copy of an article that has been posted to bit.listserv.ibm-main as well.
Dan Espen <[EMAIL PROTECTED]> writes: > Back in my insurance days on an IBM 1440, I was able to > demonstate impossibly fast state lookup times with the > simple expedient of putting NY, NJ and CA first in the table. > > Who needs binary lookups when the data cooperates. for the online internal telephone book ... used a radix search (rather than binary). basically took the first two letter frequency (in names) and built that into the search ... first probe then calculated "error" for performing the next probe. with a couple hundred thousand employees ... binary search is on the order of 16-17 probes. assuming 4k physical records (cms filesystem), radix could frequently be within the correct physical record on the first probe. the effort guidelines was that the program could be written/tested in one person week ... and the maintenance and distribution (on the internal network) of the files would be on the order of less than one person day/month. also, lookup had to be faster than lookup of paper copy sitting on desk. this was counter to a corporate hdqtrs online phone book proposal for $20m budget with dedicated 370/158 and staff. misc. past posts mentioning phone book effort: http://www.garlic.com/~lynn/2000g.html#14 IBM's mess (was: Re: What the hell is an MSX?) http://www.garlic.com/~lynn/2001j.html#29 Title Inflation http://www.garlic.com/~lynn/2001j.html#30 Title Inflation http://www.garlic.com/~lynn/2002e.html#33 Mainframers: Take back the light (spotlight, that is) http://www.garlic.com/~lynn/2003b.html#45 hyperblock drift, was filesystem structure (long warning) http://www.garlic.com/~lynn/2003i.html#58 assembler performance superiority: a given http://www.garlic.com/~lynn/2004c.html#0 A POX on you, Dennis Ritchie!!! http://www.garlic.com/~lynn/2004j.html#58 Vintage computers are better than modern crap ! http://www.garlic.com/~lynn/2004l.html#32 Shipwrecks http://www.garlic.com/~lynn/2004p.html#13 Mainframe Virus ???? http://www.garlic.com/~lynn/2005c.html#32 [Lit.] Buffer overruns http://www.garlic.com/~lynn/2005c.html#38 [Lit.] Buffer overruns http://www.garlic.com/~lynn/2005c.html#43 History of performance counters http://www.garlic.com/~lynn/2005s.html#3 Flat Query http://www.garlic.com/~lynn/2005s.html#4 Flat Query http://www.garlic.com/~lynn/2005s.html#26 IEH/IEB/... names? http://www.garlic.com/~lynn/2005t.html#44 FULIST http://www.garlic.com/~lynn/2005t.html#49 FULIST http://www.garlic.com/~lynn/2006f.html#20 Old PCs--environmental hazard http://www.garlic.com/~lynn/2006n.html#22 sorting was: The System/360 Model 20 Wasn't As Bad As All That http://www.garlic.com/~lynn/2006n.html#23 sorting was: The System/360 Model 20 Wasn't As Bad As All That http://www.garlic.com/~lynn/2006p.html#31 "25th Anniversary of the Personal Computer" http://www.garlic.com/~lynn/2006r.html#46 Trying to design low level hard disk manipulation program ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
