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Posted to issues@hive.apache.org by "ASF GitHub Bot (Jira)" <ji...@apache.org> on 2021/01/20 14:50:00 UTC
[jira] [Work logged] (HIVE-24670) DeleteReaderValue should not
allocate empty vectors for delete delta files
[ https://issues.apache.org/jira/browse/HIVE-24670?focusedWorklogId=538476&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-538476 ]
ASF GitHub Bot logged work on HIVE-24670:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 20/Jan/21 14:49
Start Date: 20/Jan/21 14:49
Worklog Time Spent: 10m
Work Description: szlta opened a new pull request #1894:
URL: https://github.com/apache/hive/pull/1894
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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Issue Time Tracking
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Worklog Id: (was: 538476)
Remaining Estimate: 0h
Time Spent: 10m
> 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
> 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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