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ASF GitHub Bot commented on DRILL-5660: --------------------------------------- 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 > Drill 1.10 queries fail due to Parquet Metadata "corruption" from DRILL-3867 > ---------------------------------------------------------------------------- > > Key: DRILL-5660 > URL: https://issues.apache.org/jira/browse/DRILL-5660 > Project: Apache Drill > Issue Type: Bug > Affects Versions: 1.11.0 > Reporter: Paul Rogers > Assignee: Vitalii Diravka > > Drill recently accepted a PR for the following bug: > DRILL-3867: Store relative paths in metadata file > This PR turned out to have a flaw which affects version compatibility. > The DRILL-3867 PR changed the format of Parquet metadata files to store > relative paths. All Drill servers after that PR create files with relative > paths. But, the version number of the file is unchanged, so that older > Drillbits don't know that they can't understand the file. > Instead, if an older Drill tries to read the file, queries fail left and > right. Drill will resolve the paths, but does so relative to the user's HDFS > home directory, which is wrong. > What should have happened is that we should have bumped the parquet metadata > file version number so that older Drillbits can’t read the file. This ticket > requests that we do that. > Now, one could argue that the lack of version number change is fine. Once a > user upgrades Drill, they won't use an old Drillbit. But, things are not that > simple: > * A developer tests a branch based on a pre-DRILL-3867 build on a cluster in > which metadata files have been created by a post-DRILL-3867 build. (This has > already occurred multiple times in our shop.) > * A user tries to upgrade to Drill 1.11, finds an issue, and needs to roll > back to Drill 1.10. Doing so will cause queries to fail due to > seemingly-corrupt metadata files. > * A user tries to do a rolling upgrade: running 1.11 on some servers, 1.10 on > others. Once a 1.11 server is installed, the metadata is updated ("corrupted" > from the perspective of 1.10) and queries fail. > Standard practice in this scenario is to: > * Bump the file version number when the file format changes, and > * Software refuses to read files with a version newer than the software was > designed for. > Of course, it is highly desirable that newer servers read old files, but that > is not the issue here. -- This message was sent by Atlassian JIRA (v6.4.14#64029)