Caching files resources

hi, i have a rails site which using caching keeping fragments in files,
the fragment piece have id the url of the relative page when generated,
example:

my-string-name-url.part=my_fragment.cache

my urls are strings longer from 40 to 80 chars.

i ask if this can cause problem of low memory in my server?

and if i using numbers instead of long string example:

1.part=my_fragment.cache

the globally resources used from caching are the sames or minor?