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https://issues.apache.org/jira/browse/DRILL-5660?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16101512#comment-16101512
]
ASF GitHub Bot commented on DRILL-5660:
---------------------------------------
Github user arina-ielchiieva commented on a diff in the pull request:
https://github.com/apache/drill/pull/877#discussion_r129530761
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/store/parquet/Metadata.java
---
@@ -132,25 +134,64 @@ public static ParquetTableMetadata_v3
getParquetTableMetadata(FileSystem fs,
}
/**
- * Get the parquet metadata for a directory by reading the metadata file
+ * Get the parquet metadata for the table by reading the metadata file
*
- * @param fs
+ * @param fs current file system
* @param path The path to the metadata file, located in the directory
that contains the parquet files
- * @return
- * @throws IOException
+ * @param metaContext metadata context
+ * @param formatConfig parquet format plugin configs
+ * @return parquet table metadata
+ * @throws IOException if metadata file can't be read or updated
*/
- public static ParquetTableMetadataBase readBlockMeta(FileSystem fs,
String path, MetadataContext metaContext, ParquetFormatConfig formatConfig)
throws IOException {
+ public static @Nullable ParquetTableMetadataBase
readBlockMeta(FileSystem fs, Path path, MetadataContext metaContext,
+ ParquetFormatConfig formatConfig) {
+ if (isMetadataFilesCorrupted(metaContext, path)) {
+ return null;
+ }
Metadata metadata = new Metadata(fs, formatConfig);
metadata.readBlockMeta(path, false, metaContext);
return metadata.parquetTableMetadata;
}
- public static ParquetTableMetadataDirs readMetadataDirs(FileSystem fs,
String path, MetadataContext metaContext, ParquetFormatConfig formatConfig)
throws IOException {
+ /**
+ * Get the parquet metadata for all subdirectories by reading the
metadata file
+ *
+ * @param fs current file system
+ * @param path The path to the metadata file, located in the directory
that contains the parquet files
+ * @param metaContext metadata context
+ * @param formatConfig parquet format plugin configs
+ * @return parquet metadata for a directory
+ * @throws IOException if metadata file can't be read or updated
+ */
+ public static @Nullable ParquetTableMetadataDirs
readMetadataDirs(FileSystem fs, Path path,
+ MetadataContext metaContext, ParquetFormatConfig formatConfig) {
+ if (isMetadataFilesCorrupted(metaContext, path)) {
+ return null;
+ }
Metadata metadata = new Metadata(fs, formatConfig);
metadata.readBlockMeta(path, true, metaContext);
return metadata.parquetTableMetadataDirs;
}
+ /**
+ * Checking whether metadata is corrupted
+ *
+ * @param metaContext metadata context
+ * @param path The path to the metadata file, located in the directory
that contains the parquet files
+ * @return true if parquet metadata is corrupted, false otherwise
+ */
+ private static boolean isMetadataFilesCorrupted(MetadataContext
metaContext, Path path) {
--- End diff --
This method does not only check if metadata files are corrupt, it also
warns the user that corrupted metadata files won't be read. Taking into account
warn message, it's better to rename method to `ignoreReadingMetadata`.
> 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
> Labels: doc-impacting
>
> 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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