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  1. IMPALA
  2. IMPALA-7637

Include more hash table stats in profile

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      Description

      Our hash table collects some useful stats about collisions and travel length, but then we don't do anything to expose them: https://github.com/apache/impala/blob/540611e863fe99b3d3ae35f8b94a745a68b9eba2/be/src/exec/hash-table.h#L989

      We should add some of them to the profile, maybe:

      • the number of probes
      • the average travel length per probe
      • the number of hash collisions
      • (optional) the number of hash table resizes. We already have the hash table size and the resize time, which I think is sufficient to debug most problems with resizes.

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            • Assignee:
              ychena Yongzhi Chen
              Reporter:
              tarmstrong Tim Armstrong
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