Tim Armstrong created IMPALA-7637:
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Summary: Include more hash table stats in profile
Key: IMPALA-7637
URL: https://issues.apache.org/jira/browse/IMPALA-7637
Project: IMPALA
Issue Type: Improvement
Components: Backend
Reporter: Tim Armstrong
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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