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  1. Lucene - Core
  2. LUCENE-5750

Speed up monotonic address access in BINARY/SORTED_SET

    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 4.9, 6.0
    • Component/s: None
    • Labels:
      None
    • Lucene Fields:
      New

      Description

      I found this while exploring LUCENE-5748, but it currently applies to both variable length BINARY and SORTED_SET, so I think its worth it to do here first.

      I think its just a holdover from before MonotonicBlockPackedWriter that to access element N we currently do:

      startOffset = (docID == 0 ? 0 : ordIndex.get(docID-1));
      endOffset = ordIndex.get(docID);
      

      Thats because previously we didnt have packed ints that supported > Integer.MAX_VALUE elements. But thats been fixed for a long time. If we just write a 0 first and do this:

      startOffset = ordIndex.get(docID);
      endOffset = ordIndex.get(docID+1);
      

      The access is then much faster. For sorting i see around 20% improvement. We don't lose any compression because we should assume the delta from 0 .. 1 is similar to any other gap N .. N+1

        Attachments

        1. LUCENE-5750.patch
          4 kB
          Robert Muir
        2. LUCENE-5750.patch
          4 kB
          Robert Muir

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            • Assignee:
              Unassigned
              Reporter:
              rcmuir Robert Muir
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              Dates

              • Created:
                Updated:
                Resolved: