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https://issues.apache.org/jira/browse/HIVE-23725?focusedWorklogId=448457&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-448457
]
ASF GitHub Bot logged work on HIVE-23725:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 19/Jun/20 13:01
Start Date: 19/Jun/20 13:01
Worklog Time Spent: 10m
Work Description: deniskuzZ commented on a change in pull request #1151:
URL: https://github.com/apache/hive/pull/1151#discussion_r442826656
##########
File path: common/src/java/org/apache/hadoop/hive/conf/HiveConf.java
##########
@@ -4979,10 +4979,11 @@ private static void
populateLlapDaemonVarsSet(Set<String> llapDaemonVarsSetLocal
HIVE_QUERY_REEXECUTION_ENABLED("hive.query.reexecution.enabled", true,
"Enable query reexecutions"),
- HIVE_QUERY_REEXECUTION_STRATEGIES("hive.query.reexecution.strategies",
"overlay,reoptimize",
+ HIVE_QUERY_REEXECUTION_STRATEGIES("hive.query.reexecution.strategies",
"overlay,reoptimize,lockacquisition",
Review comment:
I think `retry` would be a proper name.
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Issue Time Tracking
-------------------
Worklog Id: (was: 448457)
Time Spent: 0.5h (was: 20m)
> 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: 0.5h
> 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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