Word is not a database tool. Small amounts of data can be dealt with withn
it, but 1GB will exceed the maximum document size, and, even if it didn't,
performance would likely be dreadful, so, even if you want to access it from
Word, you will have to hold it somewhere else.
Strictly, how and where you sort your data, and where you ultimately hold it
are not necessarily related but if, for example, you were going to set up an
Access database, it would be better to do the work in Access.
As for Word VBA not being up to the job (of sorting), I think memory would
likely be the biggest concern - dedicated sort software would handle that
kind of thing automatically, in VBA you'd (probably) have to code up lots of
logic to have overflow storage somewhere on disk. Mechanically, WordBasic
Sort _may_ be able to do it but, again, the volume of data and the memory
required would be a concern.
At a guess you would need a minimum of 2GB (and very probably more, although
I'm not sure VBA can address more than that) of available RAM, which
probably means you would need to be running a 64-bit system - maybe, if you
have the hardware, you could give it a shot. Just try reading your data into
an array - if you can get that far, the sort might be worth a shot, but you
still have the issue of where you are going to save the sorted data, and
what way you are going to access it when it has been sorted. Using the
database as an example, again, you may not need to do the sorting yourself -
a database load function might be able to do it all behind the scenes.