The DuckDB internal storage format is currently in flux, and is expected to change with each release until we reach v1.0.0.

DuckDB files start with a uint64_t which contains a checksum for the main header, followed by four magic bytes (DUCK), followed by the storage version number in a uint64_t. A simple example of reading the storage version using python is below.

import struct

pattern = struct.Struct('<8x4sQ')

with open('test/sql/storage_version/storage_version.db', 'rb') as fh:
    print(pattern.unpack(fh.read(pattern.size)))

For changes in each given release, check out the changelog on GitHub. To see the commits that changed each storage version, see the commit log