Origin of 2GB limit when saving

Why can't we save .mat objects larger than 2GB without an orders-of-magnitude slowdown? I've read the documentation and understand that it is possible using the -v7.3 flag; I'm interested in the technical reason for the limitation, and if MathWorks has plans to fix it. It seems a bit like an old RAM limitation, but I have to imagine MathWorks would have fixed it by now if that were the case. I know that some FEX functions exist to help with this (eg serialize), and that it's possible to break up data into chunks, but it's always more of a hassle than just saving the .mat. Any insight is welcome, thank you!

Answer 1

[Walter Roberson]

The internal size fields of older mat files involve signed 32 bit values.

It might perhaps have been possible to extend to unsigned instead of signed, thus getting up to 4 gigabytes, but that would have been the limit.