5 ms·

The file has 2+ billion lines. A set or hash table won't work very if if there are, say 500 million unique strings.

• pvg 16y ago
  Hence the split. It's still likely to beat the crap out of sorting and it might not be needed, depending on the data. I do wonder what the dataset is that makes for such tiny, short lines.
  • aristus 16y ago
    Given the numbers, the need to dedupe, the poster's strong motivation and relative inexperience... I'd guess it's a gigantic spam list.
    • pvg 16y ago
      Hah, self-duh. Total failure of technical cynicism on my part.
• keefe 16y ago
  an in-memory set won't work. indexes don't have to be in memory all the time to provide log N lookup, I mean just think about how b-trees work. ...and this is a problem most databases have addressed.
  • pvg 16y ago
    It might well work, it depends a great deal on the data. In any event, I was talking about in-memory hashing, the responder's assumption that I was was correct.