[igraph] memory igraph

[Raghavendra Singh]

Hi,
I am using the C package for igraph-0.5.3
I want to create a large random graph, using erdos_renyi_game GNP:

N ~ 262144
P ~ 0.5

I am getting a memory error in vector.pmt

I have a 64 GB machine, and I dont think I can add to the memory any more. Can 
I reduce the number of bytes used by an edge and a vertex?

In any case I would like to generate a graph that is a group of erdos-renyi 
graphs, with the groups connected randomly. There would be of the order 
of 1000 nodes in each group and 256 groups. 
I was trying to create an adjacency matrix, and then use it to create a graph. 
But that seems wasteful, any suggestions?

Thanks in advance for the help,
Raghav