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From: "David Botton" <David@Botton.com>
Subject: Re: Looking for keyed file package
Date: 1999/09/26
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References: <37E817C6.80ED41E0@easystreet.com> <7saii8$5bl$1@nnrp1.deja.com>
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Newsgroups: comp.lang.ada
Date: 1999-09-27T01:58:57+00:00
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If you ever have the time to put together and example of building these keys
in Ada, I'd love to get a copy (and publish it on AdaPower if possible :-)

David Botton


Robert Dewar wrote in message <7sju61$pdv$1@nnrp1.deja.com>...
>This is a rather specialized area, and the techniques involved
>are rather tricky. To get an intuitive feeling for why the above
>is true, consider the following extremes
>
>1. Keys are very very different, in this case you only need a
>little bit of the key to differentiate them (this is trailing
>key compression in action, discarding trailing data in the
>key that is not significant).
>
>2. Keys are very very similar, in this case leading key
>compression becomes effective.
>
>The combination is effective in all situations. As I mentioned
>earlier, the technique used in the Realia COBOL compiler gets
>down to about 16 bits per key, including control information,
>pretty much regardless of key distribution.