{"record":{"id":"25559bf32a0f093c","repo":"prestodb/presto","slug":"error-decoding-values-in-encoding","errorCode":null,"errorMessage":"Error decoding  values in encoding: ","messagePattern":"Error decoding  values in encoding: ","errorType":"exception","errorClass":"UnsupportedOperationException","httpStatus":null,"severity":"error","filePath":"presto-parquet/src/main/java/com/facebook/presto/parquet/ParquetEncoding.java","lineNumber":226,"sourceCode":"            default:\n                throw new ParquetDecodingException(\"Unsupported  values type: \" + valuesType);\n        }\n    }\n\n    public boolean usesDictionary()\n    {\n        return false;\n    }\n\n    public Dictionary initDictionary(ColumnDescriptor descriptor, DictionaryPage dictionaryPage)\n            throws IOException\n    {\n        throw new UnsupportedOperationException(\" Dictionary encoding is not supported for: \" + name());\n    }\n\n    public ValuesReader getValuesReader(ColumnDescriptor descriptor, ValuesType valuesType)\n    {\n        throw new UnsupportedOperationException(\"Error decoding  values in encoding: \" + this.name());\n    }\n\n    public ValuesReader getDictionaryBasedValuesReader(ColumnDescriptor descriptor, ValuesType valuesType, Dictionary dictionary)\n    {\n        throw new UnsupportedOperationException(\" Dictionary encoding is not supported for: \" + name());\n    }\n}\n","sourceCodeStart":208,"sourceCodeEnd":234,"githubUrl":"https://github.com/prestodb/presto/blob/55bb57d202de3b926896fa966c2c4a44c779634e/presto-parquet/src/main/java/com/facebook/presto/parquet/ParquetEncoding.java#L208-L234","documentation":"Base-class sentinel in ParquetEncoding.getValuesReader: this encoding subclass does not implement a plain values reader (it is dictionary-only or a level-only encoding), so the call is an API misuse — the reader should have initialized the dictionary instead. Not triggered by file contents.","triggerScenarios":"Thrown at presto-parquet/src/main/java/com/facebook/presto/parquet/ParquetEncoding.java:226 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":["Call initDictionary and getDictionaryBasedValuesReader for dictionary encodings","Guard with usesDictionary() before choosing the reader path","Fix reader branching logic in the calling code"],"exampleFix":null,"handlingStrategy":"type-guard","validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"55bb57d202de3b926896fa966c2c4a44c779634e","analyzedAt":"2026-09-04T12:50:26.162Z","contentChangedAt":"2026-09-04T12:50:26.162Z","schemaVersion":2},"datasetVersion":"2026-09-11T21:17:09.523Z"}