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https://issues.apache.org/jira/browse/DRILL-6486?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16514448#comment-16514448
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ASF GitHub Bot commented on DRILL-6486:
---------------------------------------
sohami commented on a change in pull request #1316: DRILL-6486: BitVector split
and transfer does not work correctly for non byte-multiple transfer lengths
URL: https://github.com/apache/drill/pull/1316#discussion_r195873534
##########
File path:
exec/vector/src/main/java/org/apache/drill/exec/vector/BitVector.java
##########
@@ -328,7 +328,9 @@ public void splitAndTransferTo(int startIndex, int length,
BitVector target) {
lastButOneByte = byteIPlus1;
bitsFromLastButOneByte = (byte)((lastButOneByte & 0xFF) >>>
firstBitOffset);
- final int lastByte = this.data.getByte(firstByteIndex +
numBytesHoldingSourceBits);
+
+ final int lastByte = (8 - firstBitOffset >= length % 8) ?
+ 0 : this.data.getByte(firstByteIndex +
numBytesHoldingSourceBits);
Review comment:
Check looks good. Can you please add the motivation of this check in the
comment. Based on my understanding `length%8` gives the number of bits to be
copied from last byte and `(8-firstBitOffset)` is the bits left to be copied
from `lastButOneByte`. So if bits left to be copied is smaller than bits needed
from last byte then we need to look at next byte in those cases.
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> BitVector split and transfer does not work correctly for non byte-multiple
> transfer lengths
> -------------------------------------------------------------------------------------------
>
> Key: DRILL-6486
> URL: https://issues.apache.org/jira/browse/DRILL-6486
> Project: Apache Drill
> Issue Type: Bug
> Components: Execution - Data Types
> Affects Versions: 1.13.0
> Reporter: Karthikeyan Manivannan
> Assignee: Karthikeyan Manivannan
> Priority: Major
> Fix For: 1.14.0
>
> Attachments: TestSplitAndTransfer.java
>
> Original Estimate: 24h
> Remaining Estimate: 24h
>
> BitVector splitAndTransfer does not correctly handle transfers where the
> transfer-length is not a multiple of 8. The attached bitVector tests will
> expose this problem.
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