GH-3411 Expose row group index via Parquet reader#3412
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Fokko merged 2 commits intoapache:masterfrom Mar 12, 2026
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Seems reasonable to me, thanks @uros7251brick for working on this
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Thanks @uros7251brick 🙌 |
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Rationale for this change
Engines like Apache Spark need to know which row group a record belongs to — for example, to expose row group metadata as a hidden column, or to correlate records with row group-level statistics. Without this API, callers have no way to determine the current row group index during sequential reads.
What changes are included in this PR?
Similar to how
getCurrentRowIndex()was introduced to expose the current row's file-level index, this addsgetCurrentRowGroupIndex()to expose the index of the row group currently being read.New API:
ParquetFileReader.getCurrentRowGroupIndex()— returns the 0-based index of the last row group read viareadNextRowGroup() / readNextFilteredRowGroup(). Returns -1 before any row group has been read.ParquetReader.getCurrentRowGroupIndex()— same semantics, for the high-level record reader.ParquetRecordReader.getCurrentRowGroupIndex()— same, for the Hadoop MapReduce record reader.The returned index is the actual file-level row group index, meaning it correctly reflects gaps when empty row groups are skipped (e.g. if row group 1 is empty, the indices reported will be 0, 2, ... not 0, 1, ...).
Are these changes tested?
Yes.
Are there any user-facing changes?
No.
Closes #3411