A neat property of the parquet file format is that it’s designed with block I/O in mind, so that when you are interested in only parts of the contents of a file, it’s possible to some extent to only read that data. Many tools are aware of this property, and DuckDB is one of them. Depending on which circles you run in, a lesser known aspect of HTTP is range requests, where you specify which bytes in a file to be retrieved.
