[mattzito]

No, if you are going to change the structure of a structured document that has been saved to disk, your options are:

1) Rewrite the file to disk 2) Append the new data/metadata to the end of the existing file

I suppose you could pre-pad documents with empty blocks and then go modify those in situ by binary editing the file, but that sounds like a nightmare.

[cubefox]

Aren't there file systems that support data structures which allow editing just part of the data, like linked lists?

[PhilipRoman]

Yeah there are, Linux supports parameters FALLOC_FL_INSERT_RANGE and FALLOC_FL_COLLAPSE_RANGE for fallocate(2). Like most fancy filesystem features, they are not used by the vast majority of software because it has to run on any filesystem so you'd always need to maintain two implementations (and extensive test cases).

[layer8]

Look at the C file API which most software is based on, it simply doesn’t allow it. Writing at a given file position just overwrites existing content. There is no way to insert or remove bytes in the middle.

Apart from that, file systems manage storage in larger fixed-size blocks (commonly 4 KB). One block typically links to the next block (if any) of the same file, but that’s about the extent of it.

[formerly_proven]

No. Well yes. On mainframes.

This is why “table of contents at the end” is such an exceedingly common design choice.