Ádám Szita created HIVE-24670:
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Summary: 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
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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