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https://issues.apache.org/jira/browse/HIVE-26150?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17528326#comment-17528326
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Alessandro Solimando edited comment on HIVE-26150 at 4/26/22 5:34 PM:
----------------------------------------------------------------------

You are right, only _SortMergedDeleteEventRegistry_ uses _OrcRawRecordMerger_ 
(when memory is tight).

I found some tests covering this:
*[TestVectorizedOrcAcidRowBatchReader.java#L976|https://github.com/apache/hive/blob/a29810ce97a726fc70aecb53ebd648c3237106c4/ql/src/test/org/apache/hadoop/hive/ql/io/orc/TestVectorizedOrcAcidRowBatchReader.java#L976]
*[TestVectorizedOrcAcidRowBatchReader.java#L1113|https://github.com/apache/hive/blob/a29810ce97a726fc70aecb53ebd648c3237106c4/ql/src/test/org/apache/hadoop/hive/ql/io/orc/TestVectorizedOrcAcidRowBatchReader.java#L1113]

The issue does not reproduce there. I noticed a difference w.r.t. the failing 
tests reported in the JIRA description, that is, deletes are interleaved with 
updates in the failing case, while we have insert followed by a bunch of 
deletes in the tests mentioned right above.

I will try to modify the tests to add some updates in between deletes and see 
if I can reproduce that way.


was (Author: asolimando):
You are right, only _SortMergedDeleteEventRegistry_ uses _OrcRawRecordMerger_ 
when memory is tight. 

I found some tests covering this:
*[TestVectorizedOrcAcidRowBatchReader.java#L976|https://github.com/apache/hive/blob/a29810ce97a726fc70aecb53ebd648c3237106c4/ql/src/test/org/apache/hadoop/hive/ql/io/orc/TestVectorizedOrcAcidRowBatchReader.java#L976]
*[TestVectorizedOrcAcidRowBatchReader.java#L1113|https://github.com/apache/hive/blob/a29810ce97a726fc70aecb53ebd648c3237106c4/ql/src/test/org/apache/hadoop/hive/ql/io/orc/TestVectorizedOrcAcidRowBatchReader.java#L1113]

The issue does not reproduce there. I noticed a difference w.r.t. the failing 
tests reported in the JIRA description, that is, deletes are interleaved with 
updates in the failing case, while we have insert followed by a bunch of 
deletes in the tests mentioned right above.

I will try to modify the tests to add some updates in between deletes and see 
if I can reproduce that way.

> OrcRawRecordMerger reads each row twice
> ---------------------------------------
>
>                 Key: HIVE-26150
>                 URL: https://issues.apache.org/jira/browse/HIVE-26150
>             Project: Hive
>          Issue Type: Bug
>          Components: ORC, Transactions
>    Affects Versions: 4.0.0-alpha-2
>            Reporter: Alessandro Solimando
>            Priority: Major
>
> OrcRawRecordMerger reads each row twice, the issue does not surface since the 
> merger is only used with the parameter "collapseEvents" as true, which 
> filters out one of the two rows.
> collapseEvents true and false should produce the same result, since in 
> current acid implementation, each event has a distinct rowid, so two 
> identical rows cannot be there, this is the case only for the bug.
> In order to reproduce the issue, it is sufficient to set the second parameter 
> to false 
> [here|https://github.com/apache/hive/blob/61d4ff2be48b20df9fd24692c372ee9c2606babe/ql/src/java/org/apache/hadoop/hive/ql/io/orc/OrcInputFormat.java#L2103-L2106],
>  and run tests in TestOrcRawRecordMerger and observe two tests failing:
> {code:bash}
> mvn test -Dtest=TestOrcRawRecordMerger -pl ql
> {code}
> {noformat}
> [INFO] Results:
> [INFO]
> [ERROR] Failures:
> [ERROR]   TestOrcRawRecordMerger.testRecordReaderNewBaseAndDelta:1332 Found 
> unexpected row: (0,ignore.1)
> [ERROR]   TestOrcRawRecordMerger.testRecordReaderOldBaseAndDelta:1208 Found 
> unexpected row: (0,ignore.1)
> {noformat}



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