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https://issues.apache.org/jira/browse/SPARK-60367?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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L. C. Hsieh reassigned SPARK-60367:
-----------------------------------
Assignee: L. C. Hsieh
> Fix sliced Arrow output processors and disable slicing for runners that need
> whole batches
> ------------------------------------------------------------------------------------------
>
> Key: SPARK-60367
> URL: https://issues.apache.org/jira/browse/SPARK-60367
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 4.2.0, 4.3.0, 4.1.3, 4.4.0
> Reporter: L. C. Hsieh
> Assignee: L. C. Hsieh
> Priority: Major
> Labels: pull-request-available
>
> The sliced Arrow output processors of the Python runners (enabled by the
> internal configs spark.sql.execution.arrow.maxRecordsPerOutputBatch and
> spark.sql.execution.arrow.maxBytesPerOutputBatch, both disabled by default)
> have two bugs:
> 1. SliceRecordsArrowOutputProcessorImpl returns the whole reader root for the
> last chunk of an input batch that it has already sliced. Whenever a batch
> returned from Python has more rows than maxRecordsPerOutputBatch, the rows
> already output are output again (duplicated rows, silently wrong results).
> For example, a batch of 10 rows with maxRecordsPerOutputBatch=3 is output as
> 3, 3, 3, then the whole 10 rows.
> 2. BaseSliceArrowOutputProcessor closes the previous output root when it
> produces a different root, including the reader root itself. The reader root
> is reused for the next input batches, so when an output batch is the whole
> reader root and the next one is a slice, the next read fails, e.g. with
> IndexOutOfBoundsException from StructVector.isSet or IllegalArgumentException
> from slicing an empty vector. This affects both the records and the bytes
> slicing.
> The existing PySpark tests (MapInArrowWithOutputArrowBatchSlicing*Tests) did
> not catch this because test_different_output_length compares a set of the
> output values (which hides duplicates), and no test outputs a batch that fits
> the limit followed by one that needs slicing.
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