Apache Jena
  1. Apache Jena
  2. JENA-109

Optimise ORDER BY + OFFSET + LIMIT queries

    Details

    • Type: Improvement Improvement
    • Status: Closed
    • Priority: Minor Minor
    • Resolution: Done
    • Affects Version/s: None
    • Fix Version/s: Jena 2.11.0
    • Component/s: ARQ

      Description

      The benefits of JENA-89 gets lost as soon as someone uses OFFSET, even for low values.

      Maybe we can assume users will not hit 'next page' too many times.
      We can increase the TOPN_LIMIT_THRESHOLD in TransformTopN to 100000 and apply the same TopN optimization we discussed in JENA-89 even when we have OFFSET (when OFFSET + LIMIT < TOPN_LIMIT_THRESHOLD).
      In QueryIterTopN we simply return IteratorArray.create(y, offset, offset+limit) instead of IteratorArray.create.

      This way we can avoid total sort for a few number of small pages (all within the 100000 threshold).

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            • Assignee:
              Paolo Castagna
              Reporter:
              Paolo Castagna
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                Updated:
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                Development