Github user vdiravka commented on a diff in the pull request: https://github.com/apache/drill/pull/877#discussion_r128497802 --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/store/parquet/Metadata.java --- @@ -658,11 +657,21 @@ private boolean tableModified(List<String> directories, Path metaFilePath, return false; } + /** + * Basic class for parquet metadata. Inheritors of this class are json serializable structures of + * different versions metadata cache files. + * + * Bump up metadata major version if metadata structure is changed. + * Bump up metadata minor version if only metadata content is changed, but metadata structure is the same. + * + * Note: keep metadata versions synchronized with {@link MetadataVersion.Versions} + */ @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "metadata_version") @JsonSubTypes({ - @JsonSubTypes.Type(value = ParquetTableMetadata_v1.class, name="v1"), - @JsonSubTypes.Type(value = ParquetTableMetadata_v2.class, name="v2"), - @JsonSubTypes.Type(value = ParquetTableMetadata_v3.class, name="v3") + @JsonSubTypes.Type(value = ParquetTableMetadata_v1.class, name = MetadataVersion.Versions.Constants.V1), --- End diff -- There is no case to use `getName()` since annotations attribute value must be constant. Looks like using just constants without `enum` is more clear. Thanks
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