Use an off-the-shelf database engine, sql or good enough nosql (like esent on windows). Most file systems also have these properties, optimized for memory loca

Use an off-the-shelf database engine, sql or good enough nosql (like esent on windows). Most file systems also have these properties, optimized for memory locality (because disk seeks were incredibly slow), and you can create files in a folder much faster than O(n). If interested how they do it: https://en.wikipedia.org/wiki/B-tree https://en.wikipedia.org/wiki/B-tree