PostgreSQL Chess Extension

This is my course project for INFOH417 Database System Architecture 2023/24 at ULB. We designed a PostgreSQL extension for storing and retrieving chess games. There exist multiple notations for encoding complete chess games as well as for encoding the board status at a certain move in the game. In particular, we used Standard Algebraic Notation (SAN) to store the moves part of the Portable Game Notation (PGN), and Forsyth–Edwards Notation (FEN) to store board states.

Description

The extension implements the following datatypes

• chessboard
• chessgame

The following functions have been implemented:

• getBoard(chessgame, integer) -> chessboard: Return the board state at a given half-move (A full move is counted only when both players have played). The integer parameter indicates the count of half moves since the beginning of the game. A 0 value of this parameter means the initial board state, i.e. (rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1).
• getFirstMoves(chessgame, integer) -> chessgame: Returns the chessgame truncated to its first N half-moves. The integer parameter is zero based.
• hasOpening(chessgame, chessgame) -> bool: Returns true if the first chess game starts with the exact same set of moves as the second chess game. The second parameter should not be a full game, but should only contain the opening moves that we want to check for, which can be of any length, i.e., m half-moves.
• hasBoard(chessgame, chessboard, integer) -> bool: Returns true if the chessgame contains the given board state in its first N half-moves.

The following indices have been implemented:

• hasOpening_idx: Supports the hasOpening predicate. The index is defined on the chessgame type. Uses a B-tree, since a chessgame can be seen as a string, with a total order property.
• hasBoard_idx: Supports the hasBoard predicate. Uses the GIN index as an expression index with getAllStates(chessgame). The reason is that a chessgame can also be seen as a sequence of chessboard states. GIN would allow for indexing the individual states per chessgame.

Installation

Ensure you have installed PostgreSQL in a Linux environment (Ubuntu, WSL, etc). Then do,

make && make install

Next, open a psql session and create the extension via CREATE EXTENSION chess. The tests folder contains many examples of interacting with the extension.