parthchandra opened a new issue, #3142: URL: https://github.com/apache/parquet-java/issues/3142
### Describe the bug, including details regarding any error messages, version, and platform. The DataFusion Comet project's unit test use the ExampleParquetWriter to create Parquet files - https://github.com/apache/datafusion-comet/blob/996362e78d497c02542f1e29dbb7cba3ec16f64c/spark/src/test/scala/org/apache/spark/sql/CometTestBase.scala#L432 This was inspired by similar unit test code in Spark - https://github.com/apache/spark/blob/ece14704cc083f17689d2e0b9ab8e31cf71a7a2d/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetIOSuite.scala#L871 The output files can contain uint8 and uint16 values that are illegal per the spec. For example in this file - [alltypes_extended_plain.parquet.zip](https://github.com/user-attachments/files/18623383/alltypes_extended_plain.parquet.zip) The columns `_8` and `_9` are `uint_8` and `uint_16` values and contain illegal negative values. ``` {"_1": null, "_2": null, "_3": null, "_4": null, "_5": null, "_6": null, "_7": null, "_8": null, "_9": null, "_10": null, "_11": null, "_12": null, "_13": null, "_14": null, "_15": null, "_16": null, "_17": null, "_18": null, "_19": null, "_20": null} {"_1": null, "_2": null, "_3": null, "_4": null, "_5": null, "_6": null, "_7": null, "_8": null, "_9": null, "_10": null, "_11": null, "_12": null, "_13": null, "_14": null, "_15": null, "_16": null, "_17": null, "_18": null, "_19": null, "_20": null} {"_1": true, "_2": 18, "_3": 10002, "_4": 10002, "_5": 10002, "_6": 10002.0, "_7": 10002.0, "_8": "100021000210002100021000210002100021000210002100021000210002100021000210002100021000210002100021000210002100021000210002100021000210002100021000210002100021000210002100021000210002100021000210002100021000210002100021000210002100021000210002", "_9": -18, "_10": -10002, "_11": -10002, "_12": -10002, "_13": "10002", "_14": [50, 50, 50], "_15": 10002, "_16": 10002, "_17": [50, 50, 50, 50, 50, 50, 50, 50, 50, 50, 50, 50, 50, 50, 50, 50], "_18": 10002, "_19": 10002, "_20": 10002} {"_1": null, "_2": null, "_3": null, "_4": null, "_5": null, "_6": null, "_7": null, "_8": null, "_9": null, "_10": null, "_11": null, "_12": null, "_13": null, "_14": null, "_15": null, "_16": null, "_17": null, "_18": null, "_19": null, "_20": null} {"_1": true, "_2": 20, "_3": 10004, "_4": 10004, "_5": 10004, "_6": 10004.0, "_7": 10004.0, "_8": "100041000410004100041000410004100041000410004100041000410004100041000410004100041000410004100041000410004100041000410004100041000410004100041000410004100041000410004100041000410004100041000410004100041000410004100041000410004100041000410004", "_9": -20, "_10": -10004, "_11": -10004, "_12": -10004, "_13": "10004", "_14": [52, 52, 52], "_15": 10004, "_16": 10004, "_17": [52, 52, 52, 52, 52, 52, 52, 52, 52, 52, 52, 52, 52, 52, 52, 52], "_18": 10004, "_19": 10004, "_20": 10004} {"_1": null, "_2": null, "_3": null, "_4": null, "_5": null, "_6": null, "_7": null, "_8": null, "_9": null, "_10": null, "_11": null, "_12": null, "_13": null, "_14": null, "_15": null, "_16": null, "_17": null, "_18": null, "_19": null, "_20": null} {"_1": null, "_2": null, "_3": null, "_4": null, "_5": null, "_6": null, "_7": null, "_8": null, "_9": null, "_10": null, "_11": null, "_12": null, "_13": null, "_14": null, "_15": null, "_16": null, "_17": null, "_18": null, "_19": null, "_20": null} {"_1": null, "_2": null, "_3": null, "_4": null, "_5": null, "_6": null, "_7": null, "_8": null, "_9": null, "_10": null, "_11": null, "_12": null, "_13": null, "_14": null, "_15": null, "_16": null, "_17": null, "_18": null, "_19": null, "_20": null} {"_1": true, "_2": 24, "_3": 10008, "_4": 10008, "_5": 10008, "_6": 10008.0, "_7": 10008.0, "_8": "100081000810008100081000810008100081000810008100081000810008100081000810008100081000810008100081000810008100081000810008100081000810008100081000810008100081000810008100081000810008100081000810008100081000810008100081000810008100081000810008", "_9": -24, "_10": -10008, "_11": -10008, "_12": -10008, "_13": "10008", "_14": [56, 56, 56], "_15": 10008, "_16": 10008, "_17": [56, 56, 56, 56, 56, 56, 56, 56, 56, 56, 56, 56, 56, 56, 56, 56], "_18": 10008, "_19": 10008, "_20": 10008} {"_1": null, "_2": null, "_3": null, "_4": null, "_5": null, "_6": null, "_7": null, "_8": null, "_9": null, "_10": null, "_11": null, "_12": null, "_13": null, "_14": null, "_15": null, "_16": null, "_17": null, "_18": null, "_19": null, "_20": null} ``` Taking as an example the first value for column `_8` the bit pattern written to the file is `0xffffffee` which gets read as a negative value which is illegal for a unsigned int. The value originates in this line - https://github.com/apache/datafusion-comet/blob/996362e78d497c02542f1e29dbb7cba3ec16f64c/spark/src/test/scala/org/apache/spark/sql/CometTestBase.scala#L520 where a negative value is cast to a byte and then written to Parquet. The Parquet writer needs to cast correctly to a larger type before writing to the file. The values written can be read by the Parquet-java reader but other implementations are free to return an error or null for such values which is not desirable. ### Component(s) Core -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. 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