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Fix hash spreading in HashPartitionConsumer #4364

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Merged
merged 1 commit into from
May 13, 2024
Merged

Fix hash spreading in HashPartitionConsumer #4364

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15 changes: 15 additions & 0 deletions ydb/library/yql/dq/runtime/dq_output_consumer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,11 @@ using namespace NKikimr;
using namespace NMiniKQL;
using namespace NUdf;

inline ui64 SpreadHash(ui64 hash) {
// https://probablydance.com/2018/06/16/fibonacci-hashing-the-optimization-that-the-world-forgot-or-a-better-alternative-to-integer-modulo/
return ((unsigned __int128)hash * 11400714819323198485llu) >> 64;
}


class TDqOutputMultiConsumer : public IDqOutputConsumer {
public:
Expand Down Expand Up @@ -189,6 +194,9 @@ class TDqOutputHashPartitionConsumer : public IDqOutputConsumer {
hash = CombineHashes(hash, HashColumn(keyId, columnValue));
}


hash = SpreadHash(hash);

return hash % Outputs.size();
}

Expand All @@ -200,6 +208,8 @@ class TDqOutputHashPartitionConsumer : public IDqOutputConsumer {
hash = CombineHashes(hash, HashColumn(keyId, values[KeyColumns[keyId].Index]));
}

hash = SpreadHash(hash);

return hash % Outputs.size();
}

Expand Down Expand Up @@ -303,6 +313,8 @@ class TDqOutputHashPartitionConsumerScalar : public IDqOutputConsumer {
hash = CombineHashes(hash, HashColumn(keyId, values[KeyColumns_[keyId].Index]));
}

hash = SpreadHash(hash);

return hash % Outputs_.size();
}

Expand Down Expand Up @@ -500,6 +512,9 @@ class TDqOutputHashPartitionConsumerBlock : public IDqOutputConsumer {
}
hash = CombineHashes(hash, keyHash);
}

hash = SpreadHash(hash);

return hash % Outputs_.size();
}

Expand Down