ChessX Reference

About PGN Databases

PGN is a portable format between different chess programs, a file format, that can be written and read sequentially, but not modified at random places.

ChessX is a viewer for these files, thus ChessX is somewhat limited in handling chess data as these files can not really be handled like a proper database.

To work around some of these issues, ChessX handles smaller and larger files differently. You can configure the limit where ChessX switches the algorithm according to your computers performance.

Smaller databases are read completely into memory and can be read and written.

Larger files are only indexed and as of version 0.9.4, the index is also saved to disk for a faster reopening of a PGN file. As the games are not in memory, this algorithm does not allow saving the files again, so the database is opened read-only

The index files are saved in the index-subdirectory of the Default Data Path. If the index directory or one of its files is deleted, ChessX will recreate the Index file the next time you open the PGN file.

ChessX will open the index file instead of the PGN file if the filename fits (e.g. "chess.cxi" fits to any "chess.pgn") if the date of the last modification fits to the date stored in the index file. So ChessX won't care for the path where your PGN is located (you can relocate the file after indexing), but this limits the Index to only one file with the same basename.