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https://issues.apache.org/jira/browse/DRILL-5660?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16095006#comment-16095006
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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_r128564452
--- Diff:
exec/java-exec/src/test/java/org/apache/drill/exec/store/parquet/TestParquetMetadataCache.java
---
@@ -446,10 +447,25 @@ public void testMetadataCacheAbsolutePaths() throws
Exception {
}
}
+ @Test
--- End diff --
Two test cases are added: `testFutureUnsupportedMetadataVersion()` and
`testCorruptedMetadataFile()`.
Test first one is the test case for the future unsupported versions that is
not in the MetadataVersion.SUPPORTED_VERSIONS list. In test case `v4` is used
for now (since the last version is `v3_1`). There was `JsonMappingException`
earlier.
Other test case uses metadata file with corrupted json part. There was
`JsonParseException` earlier.
Note: To avoid any `json` deserializing exception we catch
`JsonProcessingException` (parent class of the above ones).
> 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.
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