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https://issues.apache.org/jira/browse/HIVE-21531?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16824551#comment-16824551
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Ashutosh Chauhan commented on HIVE-21531:
-----------------------------------------
+1
> Vectorization: all NULL hashcodes are not computed using Murmur3
> ----------------------------------------------------------------
>
> Key: HIVE-21531
> URL: https://issues.apache.org/jira/browse/HIVE-21531
> Project: Hive
> Issue Type: Bug
> Affects Versions: 4.0.0, 3.1.1
> Reporter: Gopal V
> Assignee: Gopal V
> Priority: Critical
> Attachments: HIVE-21531.1.patch, HIVE-21531.1.patch,
> HIVE-21531.WIP.patch
>
>
> The comments in Vectorized hash computation call out the MurmurHash
> implementation (the one using 0x5bd1e995), while the non-vectorized codepath
> calls out the Murmur3 one (using 0xcc9e2d51).
> The comments here are wrong
> {code}
> /**
> * Batch compute the hash codes for all the serialized keys.
> *
> * NOTE: MAJOR MAJOR ASSUMPTION:
> * We assume that HashCodeUtil.murmurHash produces the same result
> * as MurmurHash.hash with seed = 0 (the method used by
> ReduceSinkOperator for
> * UNIFORM distribution).
> */
> protected void computeSerializedHashCodes() {
> int offset = 0;
> int keyLength;
> byte[] bytes = output.getData();
> for (int i = 0; i < nonNullKeyCount; i++) {
> keyLength = serializedKeyLengths[i];
> hashCodes[i] = Murmur3.hash32(bytes, offset, keyLength, 0);
> offset += keyLength;
> }
> }
> {code}
> but the wrong comment is followed in the Vector RS operator
> {code}
> System.arraycopy(nullKeyOutput.getData(), 0, nullBytes, 0,
> nullBytesLength);
> nullKeyHashCode = HashCodeUtil.calculateBytesHashCode(nullBytes, 0,
> nullBytesLength);
> {code}
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