size of data stored in gist index

Hello,

I try to index histograms in my table. For this I uses the cube contrib
module in which I removed the dimension check. If the cube has more than
255 dimensions, for example 256 ^= 4 + 4 + 256 * 2 * 8 = 4104 bytes, this
data can not be stored in the gist index any more. If I try it, I get the
following error:

PANIC:  failed to add item to index page in "histogram_idx"

Do I have to compress the data in any way or is it possible, to store index
data with this huge size?

Thanks,
  Gerhard