HIVE-28503: Vectorization: concat (||) on string columns returns NULL for non-null inputs#6607
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maheshrajus wants to merge 2 commits into
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HIVE-28503: Vectorization: concat (||) on string columns returns NULL for non-null inputs#6607maheshrajus wants to merge 2 commits into
maheshrajus wants to merge 2 commits into
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… for non-null input
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rubenada
approved these changes
Jul 21, 2026
deniskuzZ
reviewed
Jul 23, 2026
| /* | ||
| * Do careful maintenance of the outputColVector.noNulls flag. | ||
| * | ||
| * HIVE-28503: when both inputs have noNulls=true the output vector(outV) must set true. |
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please keep the comment concise and clear. No need to mention HIVE-28503
deniskuzZ
reviewed
Jul 23, 2026
| * sibling scalar variants (StringGroupColConcatStringScalar and | ||
| * StringScalarConcatStringGroupCol) already do on their no-nulls paths. | ||
| */ | ||
| outV.noNulls = true; |
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@maheshrajus should we do instead
if (!outV.noNulls) {
// Assume it is almost always a performance win to fill all of isNull so we can
// safely reset noNulls.
Arrays.fill(outV.isNull, false);
outV.noNulls = true;
}
same pattern is used in other places
deniskuzZ
requested changes
Jul 23, 2026
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Thank you @deniskuzZ for the review. I will check and address the comments. |
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What changes were proposed in this pull request?
Why are the changes needed?
The output BytesColumnVector(outV) is reused across batches. A previous batch that went through a null-carrying branch leaves outV.noNulls = false. The no-nulls branch wrote per-row isNull[i] = false but never reset outV.noNulls = true, so downstream vectorized consumers that utilizes on noNulls treated fully-populated rows as NULL and producing NULL for a || b on rows where both operands were non-null.
More code level details we can find in the jira: https://issues.apache.org/jira/browse/HIVE-28503
Does this PR introduce any user-facing change?
No
How was this patch tested?
With added unit tests