[Enhancement] use crc hash for exchange op when hash partition #63726
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Signed-off-by: before-Sunrise <[email protected]>
Signed-off-by: before-Sunrise <[email protected]>
Signed-off-by: before-Sunrise <[email protected]>
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alvin-celerdata
requested changes
Sep 30, 2025
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alvin-celerdata
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alvin-celerdata
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I put a request changes first before the concerns are resolved.
| _hash_values.assign(num_rows, HashUtil::FNV_SEED); | ||
| for (const ColumnPtr& column : _partitions_columns) { | ||
| column->fnv_hash(&_hash_values[0], 0, num_rows); | ||
| // Check if we should use crc32_hash instead of fnv_hash based on session variable |
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What hash function does starrocks use for aggregation.
The hash functions of aggregation and shuffle should be different, otherwise, it will cause a lot of hash conflicts in aggregation or hash-join. It will cause a much bigger hash table than it should be.
So when you change it, you must make sure that they are using two different functions.
[Java-Extensions Incremental Coverage Report]✅ pass : 0 / 0 (0%) |
[BE Incremental Coverage Report]❌ fail : 0 / 5 (00.00%) file detail
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Why I'm doing:
fnv hash is much slower then crc hash.
What I'm doing:
use crc hash when sv is set. So upgrade is safe
What type of PR is this:
Does this PR entail a change in behavior?
If yes, please specify the type of change:
Checklist:
Bugfix cherry-pick branch check: