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Subject: Re: Value of 2-bit tables

Author: David Blackman

Date: 23:43:44 01/31/01

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On January 31, 2001 at 19:14:19, Dann Corbit wrote:

>On January 31, 2001 at 11:36:01, Robert Hyatt wrote:
>[snip]
>>The idea seems pretty good for 3-4 piece files, and even for 5 piece files
>>although the memory to hold them becomes prodigous.  But 6's are hopeless
>>as todays machines are no better at probing a 1gb file than they are at
>>probing a 1 terrabyte file.
>
>It might be worthwhile to store them in a real database with hashed index.
>
>Modern database systems will cache database requests very efficiently, and so I
>think it might be doable.  The database model would be the hard part (finding a
>representation which is still highly compact like the tablebase files)

Modern database systems are pretty hopeless for raw speed and space efficiency.
A custom built data structure is almost always faster and smaller, and usually
much simpler as well.

The good things about modern database systems, are safe multiuser access and
update, robustness in the face of various disasters including hardware failure,
reliable backups that can be done even while transactions are in progress, nice
system administration tools, nice programming tools for building simple GUI
programs for end users, a highly generalised and flexible query mechanism, and
so on.

All of these good things are irrelevant for endgame tablebases, and the
performance cost would really hurt.



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