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From: preece@uicsl.UUCP
Newsgroups: net.micro.pc
Subject: Re: RE: 99 files and 20 open files - (nf)
Message-ID: <3049@uiucdcs.UUCP>
Date: Thu, 29-Sep-83 22:52:25 EDT
Article-I.D.: uiucdcs.3049
Posted: Thu Sep 29 22:52:25 1983
Date-Received: Sun, 2-Oct-83 04:22:50 EDT
Lines: 27

#R:microsof:-865600:uicsl:7300009:000:1158
uicsl!preece    Sep 29 09:13:00 1983

	I wonder about applications the 'require' > 20 files open at a
	particular time.
----------
I'll give you an easy example of a program that very naturally uses
more than twenty files. Consider the problem of indexing a large
file of text. We have to break out all the individual words and,
subsequently, sort them into lexicographic order. A very useful
method here is the distribution sort. The most obvious way to do it
is to partition the words by first letter. This requires 26 output
files in addition to the input file. Obviously the letters can be
grouped (since they are not equi-frequent), but the most natural way
is to just use the obvious distribution.

Another obvious example is a large database management system in which
relations are separate files. A reasonably complex model, with
attendant index files, could easily get over 20 files.

It's quite possible to have situations where the natural approach
requires a lot of files. Such situations can generally be re-cast
to use a smaller number, but the change usually makes the process
involved less intuitive and therefore less easy to maintain.

scott preece
pur-ee!uiucdcs!uicsl!preece