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https://issues.apache.org/jira/browse/DRILL-5660?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16102074#comment-16102074
]
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_r129654624
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/store/parquet/MetadataVersions.java
---
@@ -0,0 +1,115 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ * <p/>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p/>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.drill.exec.store.parquet;
+
+import com.google.common.collect.Lists;
+import org.apache.drill.common.Version;
+import org.apache.drill.common.exceptions.DrillRuntimeException;
+
+import java.util.List;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * Supported metadata versions.
+ * <p>
+ * Note: keep them synchronized with {@link
Metadata.ParquetTableMetadataBase} versions
+ */
+public class MetadataVersions {
+ static final org.slf4j.Logger logger =
org.slf4j.LoggerFactory.getLogger(Metadata.class);
+
+ /**
+ * Version 1: Introduces parquet file metadata caching.<br>
+ * See DRILL-2743
+ */
+ public static final String V1 = "v1";
+ /**
+ * Version 2: Metadata cache file size is reduced.<br>
+ * See DRILL-4053
+ */
+ public static final String V2 = "v2";
+ /**
+ * Version 3: Difference between v3 and v2 : min/max, type_length,
precision, scale, repetitionLevel, definitionLevel.<br>
+ * Filter pushdown for Parquet is implemented. <br>
+ * See DRILL-1950
+ */
+ public static final String V3 = "v3";
+ /**
+ * Version 3.1: Absolute paths of files and directories are replaced
with relative ones.<br>
+ * See DRILL-3867
+ */
+ public static final String V3_1 = "v3.1";
+
+ /**
+ * All historical versions of the Drill metadata cache files
+ */
+ public static final List<String> SUPPORTED_VERSIONS =
Lists.newArrayList(V1, V2, V3, V3_1);
--- End diff --
`MetadataVersion` is created.
> 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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