Author: Dann Corbit
Date: 11:59:57 07/17/02
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On July 17, 2002 at 14:36:29, Dieter Buerssner wrote: [snip] >Did you check, if this is worth the work? Do you get now and then opening moves >by the probing of the mirrored position? How often? Once in 10 games, in 100 >games? ... It depends to a great extent on the density of your database. If you have 3 positions, you will not find many hits. If you have 30 million positions, you will find lots of them. From some percursory analysis of the CAP project data, I think that once you have a million positions in your database, you will get about one transform hit per hundred thousand, and then it will increase steadily as you add more positions. I base that on my initial work with the project. My first build had the database not case sensitive. I had a unique clustered index on the EPD position with ignore duplicates. As I added more and more data, I started to see a few rejections in the first few hundred thousand rows. As it grew over a million, I had so many hits I investigated to find that I was getting rejected rows where the pieces were all identical, but some colors of the pieces were different. Obviously, I had to make a new database that was case sensitive and reload the data. Sample where a case insensitive server would reject the transaction with "identical key": [D]3k4/5n2/8/8/1n6/5N2/8/3K4 w - - [D]3k4/5n2/8/8/1N6/5N2/8/3K4 w - - If you have hundreds of millions of positions in your database, you will get a huge number of successful transformations. If you have a very small database, it is a waste of time. IMO-YMMV
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