[Nauty-list] Maximum file size that shortg can handle

[Brendan McKay]

shortg reads the graphs, canonically labels them, and passes them
down a pipe to a subprocess that runs the system 'sort' program.
Then it reads the output from the subprocess and does what is
required with it.

There is no reason in principle why shortg cannot handle files as
large as the system sort program can handle.  The only problem I 
see in the program is that it uses "unsigned long int" counters
to number the graphs, so if that type has only 32 bits the counts
will be wrong if there are 2^32 or more graphs.  That's enough to
get to about 3TB of 50-vertex graphs in graph6 format.  On my long
list of things to do is to make such counters type long long so
this limit will disappear eventually.

Incidentally, for really huge problems it is a good idea to check
a sample of graphs to see if sparse6 or graph6 format is the most
compact.  The easiest way to convert is copyg.

Brendan.


* Bulutoglu Dursun A Civ AFIT/ENC <Dursun.Bulutoglu at afit.edu> [080729 09:26]:
> I was wondering what the largest file size shortg can handle in a 64 bit
> system is.
> A 64 bit system supports files up to 4x10^18 bytes of size.
> For example would it be possible to shortg a file of size 10 Terabytes?
> 
> Thanks in advance.
> Dursun.

> _______________________________________________
> Nauty-list mailing list
> Nauty-list at cs.anu.edu.au
> http://dcsmail.anu.edu.au/cgi-bin/mailman/listinfo/nauty-list