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https://issues.apache.org/jira/browse/HIVE-17124?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Gopal V updated HIVE-17124:
---------------------------
Status: Patch Available (was: Open)
> PlanUtils: Rand() is not a failure-tolerant distribution column
> ---------------------------------------------------------------
>
> Key: HIVE-17124
> URL: https://issues.apache.org/jira/browse/HIVE-17124
> Project: Hive
> Issue Type: Bug
> Components: Query Planning
> Affects Versions: 2.3.0, 3.0.0
> Reporter: Gopal V
> Assignee: Gopal V
> Priority: Major
> Attachments: HIVE-17124.1.patch
>
>
> {code}
> else {
> // numPartitionFields = -1 means random partitioning
>
> partitionCols.add(TypeCheckProcFactory.DefaultExprProcessor.getFuncExprNodeDesc("rand"));
> }
> {code}
> This causes known data corruption during failure tolerance operations.
> There is a failure tolerant distribution function inside ReduceSinkOperator,
> which kicks in automatically when using no partition columns
> {code}
> if (partitionEval.length == 0) {
> // If no partition cols, just distribute the data uniformly
> // to provide better load balance. If the requirement is to have a
> single reducer, we should
> // set the number of reducers to 1. Use a constant seed to make the
> code deterministic.
> if (random == null) {
> random = new Random(12345);
> }
> keyHashCode = random.nextInt();
> }
> {code}
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