chess_pos_db

chess_pos_db is a free, opensource software aiming to provide a high performance database service for aggregation of chess position data from chess games. It provides a simple TCP interface for interprocess communication, a console interface, and an optional windows GUI. The goal is to achieve cutting-edge performance and unmatched possibilities.

For a Windows GUI see HERE. It also contains setup instructions.

Notable features:

• 3 data formats allowing different tradeoff between space and information stored.

• Creation of a position database from PGN or BCGN files. Data being agreggated (depends on database format chosen):

  • Win count from a given position
  • Draw count from a given position
  • Loss count from a given position
  • Total elo difference for players that reach a given position (average = total / game_count)
  • Some PGN Tags (result, event, white, black, plies, ECO) of the first (depending on database format also last) game with this position.

• High performance and little storage

  • On modern hardware and fast storage it can import between 4 to 10 million positions per second depending on the database format chosen.
  • Each unique position entry takes between 16 to 32 bytes depending on the format used. For typical large dataset only about 70% or less of the positions are unique.
  • Querying is optimized for minimal number of disk seeks. For example for the db_beta format querying all data for a single move and all possible moves takes ~1 second an HDD and is blazingly fast on an SSD.
  • Index kept in RAM, uses orders of magnitude times less space than the database and accelerates the queries (size globally configurable).

• High limits

  • Can handle trillions of positions
  • Up to 4 billion games (can be increased in the future, and some formats may work with higher numbers)
  • No limit on input/output file sizes (can handle large PGN files). The only limit is from the filesystem.

• Distinction between continuations (exact move played to arrive at this position) and transpositions (different move played to arrive at this position).

• Local, file based database structure allowing for easy archiving, copying, and distribution.

• Extensive configuration. (see cfg/config.json)

• Console user interface

• A simple TCP server allowing managing and quering databases.

Notable codebase features:

• High performance streaming PGN parser with varying degree of validation
• SAN move parser with varying degree of validation
• Support for BCGN - a more space efficient alternative to PGN.
• Clean chess abstraction. Parts can be used as a chess library.
• External algorithms with support for async IO through worker threads.
• Various integer compression schemes

Building

Currently only Windows is explicitly supported. Though the code is mostly standard compliant C++17 - there are only a few instances of non-portable code, most notably 64 bit file seek functions in External module. Not tested on systems other that Windows.

Requires 64-bit builds to work as intended. May not compile or have bugs on 32-bit builds.

Compiles with Visual Studio 2019 MSVC Compiler (.sln included).

Support for other compilers and other operating systems is planned but there is no definitive deadline.

Dependencies

Licenses specified in header files or in respective folders.

• libcppjson - included in /lib folder
• xxhash - included in /lib folder
• googletest - vcpkg
• brynet - vcpkg

UI

For a Windows GUI see HERE. It also contains setup instructions.

It's a command line application with 3 modes of operation:

1. When launched without any command line arguments

   • Provides basic console interface functionality for creating/opening/querying/closing/destroying databases. See help command.
   • Currently supports only one hardcoded database format.

2. When launched with 2 parameters <db_path> <port>

   • Opens a database under <db_path>
   • Creates a TCP server listening on <port> and accepts query requests (see docs for specification).
   • Responses are sent back through the same TCP connection.

3. When launched with 1 parameter <port>

   • Creates a TCP server listening on <port> and accepts various commands (see docs). For example:

     • creating a database
     • merging a database
     • opening a database
     • querying

   • The interface is stateful - only one database can exist at once. Currently only one simultanuous connection is supported.

   • Not meant for remote use. Can function as an interprogram messaging protocol.