You can append just fine, and SQLite doesn't let you replace arbitrary content either. If the new content fits within the space of what it is overwriting then

You can append just fine, and SQLite doesn't let you replace arbitrary content either. If the new content fits within the space of what it is overwriting then all is fine (as with zip), but if there is insufficient space then the new data is written at the end (as with zip). SQLite has a vacuum command which creates a new database only with used content.