Re: opening large files (few hundred meg)

[Stefan Monnier]

> I can't see a use case for editing extremely large files with a text
> editor and I think there are plenty of good tools for this already. The
> fact that once you move to a 64 bit platform, the maximum file size
> increases to the point that means there would be even less need/demand
> for special modes to edit files too large to be read into emacs in one
> go.Personally, I'd rather see effort put towards other areas which would

Actually, I've several times had to look for something specific and
maybe even change it in some very large file.  The kind of situation
where this occurred made it difficult to use other tools because
I wasn't quite sure what I was looking for (regexp isearch is great for
that) and because the file was often binary, so line-oriented tools
don't work so well.  Yes, I could probably have done it with other
tools, but doing it with Emacs was easier.

Luckily, while large those were not larger than Emacs's limits.
But even tho Emacs could handle them, it had trouble handling them
because of the time it took to load the file and the swapping it caused.
On a 64bit system, you should be able to load a 10GB file if you feel
like it, but based on my knowledge of Emacs's internals, I can assure
you that you'll bump into bugs (many places where we turn 64bit Elisp
integers into 32bit C "int"), and that unless your machine has more than
16GB of RAM, it'll be painfully slow.  So some major mode to browse and
even edit very large files does sound like a good idea, even in
a 64bit world.  But it's not nearly high enough on my todo list to have
a chance in the next ... 10 years?


        Stefan