I used to keep it in SQLite (much easier to distribute than PostgreSQL). It worked a lot better than many other options I tried. However, rebuilding the databas

I used to keep it in SQLite (much easier to distribute than PostgreSQL). It worked a lot better than many other options I tried. However, rebuilding the database from updated data would take more than a day, and some queries were too slow. Switching to PostgreSQL sped things up, at the cost of requiring a separate database process, dealing with psql's weird access control, and adding an inconvenient step of loading the data using COPY commands.