The number of values in a miniblock should be multiple of 32 instead of 8 in DeltaBinaryPackingConfig
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Description
In the code of [DeltaBinaryPackingValuesWriter](https://github.com/apache/parquet-mr/blob/master/parquet-column/src/main/java/org/apache/parquet/column/values/delta/DeltaBinaryPackingValuesWriter.java#L82), the parameters are always DEFAULT_NUM_BLOCK_VALUES(which is 128) and DEFAULT_NUM_MINIBLOCKS(which is 4). So if the file is written by parquet-mr, the number of values in a miniblock is always 32. It is consistent with the [spec.](https://github.com/apache/parquet-format/blob/master/Encodings.md#delta-encoding-delta_binary_packed--5)
However, the code in [DeltaBinaryPackingConfig](https://github.com/apache/parquet-mr/blob/master/parquet-column/src/main/java/org/apache/parquet/column/values/delta/DeltaBinaryPackingConfig.java#L41) indicates that the number of values in a miniblock must be multiple of 8. Would it be better if the limitation was changed to 32?
**Reporter**: [Shan Huang](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=shanhuang) / @shanhuuang
**Note**: *This issue was originally created as [PARQUET-2077](https://issues.apache.org/jira/browse/PARQUET-2077). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*
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Research direction
Read DeltaBinaryPackingConfig.java and compare its miniblock-size validation with DeltaBinaryPackingValuesWriter.java and the Delta Binary Packed specification. Confirm that the accepted miniblock value count matches the specification and the writer's 128-value, four-miniblock configuration, then run the relevant parquet-column tests if available.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- java
- Domain
- data-engineering
- Issue type
- Bug
- Difficulty
- 2/5
- Estimated time
- 1-3 hours
- Activity status
- Stale
- Clarity
- Clearly specified
- Newbie friendliness
- 45/100