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https://issues.apache.org/jira/browse/IMPALA-12765?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Zoltán Borók-Nagy reassigned IMPALA-12765:
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Assignee: Zoltán Borók-Nagy
> Balance consecutive partitions better for Iceberg tables
> --------------------------------------------------------
>
> Key: IMPALA-12765
> URL: https://issues.apache.org/jira/browse/IMPALA-12765
> Project: IMPALA
> Issue Type: Bug
> Components: Frontend
> Reporter: Zoltán Borók-Nagy
> Assignee: Zoltán Borók-Nagy
> Priority: Major
> Labels: impala-iceberg
>
> During scheduling Impala does the following:
> * Non-Iceberg tables
> ** The scheduler processes the scan ranges in partition key order
> ** The scheduler selects N replicas as candidates
> ** The scheduler chooses the executor from the candidates based on minimum
> number of assigned bytes
> ** So consecutive partitions are more likely to be assigned to different
> executors
> * Iceberg tables
> ** The scheduler processes the scan ranges in random order
> ** The scheduler selects N replicas as candidates
> ** The scheduler chooses the executor from the candidates based on minimum
> number of assigned bytes
> ** So consecutive partitions (by partition key order) are assigned randomly,
> i.e. there's a higher chances of clustering
> If the IcebergScanNode ordered its file descriptors based on their paths we
> would have a more balanced scheduling for consecutive partitions. Queries
> that operate on a range of partitions are quite common, so it makes sense to
> optimize that case.
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