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https://issues.apache.org/jira/browse/HIVE-23725?focusedWorklogId=479606&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-479606
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ASF GitHub Bot logged work on HIVE-23725:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 07/Sep/20 11:38
Start Date: 07/Sep/20 11:38
Worklog Time Spent: 10m
Work Description: deniskuzZ opened a new pull request #1474:
URL: https://github.com/apache/hive/pull/1474
…l reads (Peter Varga, reviewed by Jesus Camacho Rodriguez, Denys Kuzmenko)"
This reverts commit e2a02f1b43cba657d4d1c16ead091072be5fe834.
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reverts https://issues.apache.org/jira/browse/HIVE-23725
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doesn't completely solve the problem described in a JIRA, will be replaced
with another solution
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No
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Issue Time Tracking
-------------------
Worklog Id: (was: 479606)
Time Spent: 5h 50m (was: 5h 40m)
> ValidTxnManager snapshot outdating causing partial reads in merge insert
> ------------------------------------------------------------------------
>
> Key: HIVE-23725
> URL: https://issues.apache.org/jira/browse/HIVE-23725
> Project: Hive
> Issue Type: Bug
> Reporter: Peter Varga
> Assignee: Peter Varga
> Priority: Major
> Labels: pull-request-available
> Time Spent: 5h 50m
> Remaining Estimate: 0h
>
> When the ValidTxnManager invalidates the snapshot during merge insert and
> starts to read committed transactions that were not committed when the query
> compilation happened, it can cause partial read problems if the committed
> transaction created new partition in the source or target table.
> The solution should be not only fix the snapshot but also recompile the query
> and acquire the locks again.
> You could construct an example like this:
> 1. open and compile transaction 1 that merge inserts data from a partitioned
> source table that has a few partition.
> 2. Open, run and commit transaction 2 that inserts data to an old and a new
> partition to the source table.
> 3. Open, run and commit transaction 3 that inserts data to the target table
> of the merge statement, that will retrigger a snapshot generation in
> transaction 1.
> 4. Run transaction 1, the snapshot will be regenerated, and it will read
> partial data from transaction 2 breaking the ACID properties.
> Different setup.
> Switch the transaction order:
> 1. compile transaction 1 that inserts data to an old and a new partition of
> the source table.
> 2. compile transaction 2 that insert data to the target table
> 2. compile transaction 3 that merge inserts data from the source table to the
> target table
> 3. run and commit transaction 1
> 4. run and commit transaction 2
> 5. run transaction 3, since it cointains 1 and 2 in its snaphot the
> isValidTxnListState will be triggered and we do a partial read of the
> transaction 1 for the same reasons.
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