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https://issues.apache.org/jira/browse/SPARK-59902?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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L. C. Hsieh updated SPARK-59902:
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Affects Version/s: 4.3.0
4.4.0
(was: 5.0.0)
> Detect BYTE_STREAM_SPLIT pages with more encoded values than non-null values
> in the vectorized reader
> -----------------------------------------------------------------------------------------------------
>
> Key: SPARK-59902
> URL: https://issues.apache.org/jira/browse/SPARK-59902
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 4.3.0, 4.4.0
> Reporter: L. C. Hsieh
> Priority: Major
>
> Follow-up of SPARK-59831.
> For a column with definition levels, the vectorized BYTE_STREAM_SPLIT reader
> ({{VectorizedByteStreamSplitValuesReader}}) cannot check the number of
> encoded values against the page header when the page is initialized: the page
> value count includes nulls, so it is only an upper bound. Let D be the number
> of non-null definition levels of a page and E the number of encoded values.
> * E < D fails with a {{ParquetDecodingException}} once a read or skip runs
> past the last encoded value (since SPARK-59831).
> * E > D is never detected, even when the page is read to its end. The values
> are decoded with the wrong stream stride, so a corrupt data section can
> return wrong values without an error. For example, an optional FLOAT page
> with {{num_values = 10}}, 5 non-null levels and 24 data bytes (E = 6) is read
> as 5 values with a stride of 6.
> This could be detected without {{DataPageV2}}'s {{num_nulls}} (which no
> reader validates today): when {{VectorizedColumnReader.readBatch}} has
> consumed all levels of a page ({{readState.valuesToReadInPage == 0}} right
> after the {{defColumn.readBatch}} / {{repColumn.readBatchRepeated}} calls),
> all encoded values must have been consumed too. A no-op default hook on
> {{VectorizedValuesReader}}, implemented by this reader as {{offset ==
> valueCount}}, would check it once per page. Checking only before the next
> {{readPage()}} would miss the last page of a column chunk.
> A prototype of this check found no false positive on 1454 pages of the
> BYTE_STREAM_SPLIT tests in the Parquet suites (arrays, nullable columns and
> column index row ranges, with v1 and v2 pages). Since a false positive would
> reject valid files, it should be verified on more layouts (nested structs and
> maps, row ranges on nested columns) before it is added. It is still a late
> check, so a query that stops before the end of a page does not reach it.
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