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https://issues.apache.org/jira/browse/HIVE-24670?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Work on HIVE-24670 started by Ádám Szita.
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> DeleteReaderValue should not allocate empty vectors for delete delta files
> --------------------------------------------------------------------------
>
> Key: HIVE-24670
> URL: https://issues.apache.org/jira/browse/HIVE-24670
> Project: Hive
> Issue Type: Improvement
> Reporter: Ádám Szita
> Assignee: Ádám Szita
> Priority: Major
> Labels: pull-request-available
> Time Spent: 10m
> Remaining Estimate: 0h
>
> If delete delta caching is turned off, the plain record reader inside
> DeleteReaderValue allocates a batch with a schema that is equivalent to that
> of an insert delta.
> This is unnecessary as the struct part in a delete delta file is always
> empty. In cases where we have many delete delta files (e.g. due to compaction
> failures) and a wide table definition (e.g. 200+ cols) this puts a
> significant amount of memory pressure on the executor, while these empty
> structures will never be filled or otherwise utilized.
> I propose we specify an ACID schema with an empty struct part to this record
> reader to counter this.
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