How to work with one very large text table but not in memory

[tsbockman]

On Tuesday, 6 April 2021 at 19:55:03 UTC, Alain De Vos wrote:
> I have one very large text table I want to work with.
> But I don't want to keep de table in memory, what do I use ?
> Using an sql database is overkill in my setting.
> There are 10 colums but millions of rows.

You might find memory mapped files useful: 
http://phobos.dpldocs.info/std.mmfile.MmFile.html

This allows D code to access the entire contents of the file as 
though it were a giant byte array in RAM, without requiring that 
there actually be enough physical RAM available to really do 
that. The OS is responsible for paging data to and from the disk 
as it is accessed.