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  1. Calcite
  2. CALCITE-3785

Performance regression in HepPlanner#belongsToDag() due to expensive hashCode computation

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Details

    • Bug
    • Status: Closed
    • Major
    • Resolution: Fixed
    • None
    • 1.22.0
    • None

    Description

      It turns out that the change in CALCITE-3713 added an extra overhead of 20~30% HepPlanner. The hash map lookup in belongsToDag becomes much slower due to expensive computation of the hashcode and equals for the list.

      A simple profiling of the planner before and after CALCITE-3713 is shown below.

      To test whether or not a vertex belongs to DAG, we can simply do graph.vertexSet().contains(vertex); There's no need to look up in mapDigestToVertex map, which incurs overhead of creating the map key. This problem was amplified by CALCITE-3713.

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        1. after.png
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          Stamatis Zampetakis
        2. before.png
          16 kB
          Stamatis Zampetakis

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              Unassigned Unassigned
              xndai Xiening Dai
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