so let's see if I'm reading this right: but you don't say how many distinct keys there are (i.e., how finely binning is grouping things).

But it doesn't matter. For every single key you are doing a linear search through every file. So that's (number of keys) * 100,000,000 matrices to wade through; no wonder this is slow.

You need to be writing each %small_hash in sorted order. Sorting 1000 small_hashes will be faster than sorting the big hash (1000*(n/1000)*log(n/1000) = n log(n/1000) < n log(n) but the really important thing is this will enable the merge I was talking about before, which only reads each file once rather than once for every key value.


In reply to Re^3: how to merge many files of sorted hashes? by wrog
in thread how to merge many files of sorted hashes? by andromedia33

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