RE: [Bug-gnubg] Bug: 14 point one-sided race database withmakebearoff.exe

[Ian Shaw]

From: Øystein Johansen
Sent: 05 January 2005 21:15

> Joachim Matussek wrote:
> | Hello,
> |
> | i tried to create one-sided race databases with makebearoff.exe. At 
> | first i created one for 13 points which worked well.
> |
> | Afterwards i tried 14 points but the program stopped when the temp 
> | file reached a size of about 2,1 GB (2147483647 bytes). I 
> tried under 
> | Windows with NTFS as well as under Linux with FAT32. Error message 
> | under Linux was "File size limit exceeded". I don´t 
> remember the error  
> | message under Windows but I think it was an internal message of the 
> | .exe.
> 
> Hmmmmm.... this sounds familiar. Hasn't this been reported 
> before? I may be wrong but wasn't it Morten Wang who reported 
> this problem years ago?
> Or maybe it was Ian?
> 
> If I remember correctly Ian (Shaw) and Morten are the two 
> users who have built the biggest bearoff databases. Maybe one 
> of them knows something?
> 
> Worst case we could make a limit of 13 point for the one 
> sided database.
> This would be a bad solution though since storeage of several 
> Gigabytes is no problem anymore.
> 

There is a limit on the file size that the PC file system can handle. It is 
2^31 bytes = 2147483647. I assume it's 2^31 instead of 2^32 because the 32nd 
bit is used as the +/- sign.

Anyway, this puts a limit on the size of the database. 13 points works but 14 
doesn't, as you have seen.

On a related note, I've been wondering if the two sided database could be 
compressed by omitting gin positions, that is, positions where one side is 
guaranteed a win but no gammon is possible. This out to have a greater and 
greater effect as the size of the database increases, since you will have more 
and more lop-sided positions.

-- Ian