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https://issues.apache.org/jira/browse/DRILL-5660?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16101513#comment-16101513
]
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_r129526936
--- 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);
+
+ /**
+ * @param metadataVersion parquet metadata version
+ * @return true if metadata version is supported, false otherwise
+ */
+ public static boolean isVersionSupported(String metadataVersion) {
+ return SUPPORTED_VERSIONS.contains(metadataVersion);
+ }
+
+ /**
+ * Helper compare method similar to {@link java.util.Comparator#compare}
+ *
+ * @param metadataVersion1 the first metadata version to be compared
+ * @param metadataVersion2 the second metadata version to be compared
+ * @return a negative integer, zero, or a positive integer as the
+ * first argument is less than, equal to, or greater than the
+ * second.
+ */
+ public static int compare(String metadataVersion1, String
metadataVersion2) {
+ if (isVersionSupported(metadataVersion1) &&
isVersionSupported(metadataVersion2)) {
+ return
VersionParser.parse(metadataVersion1).compareTo(VersionParser.parse(metadataVersion2));
+ } else {
+ // this is never reached
+ throw new DrillRuntimeException(String.format("Unsupported metadata
version. '%s' version can't be compared with '%s'",
+ metadataVersion1, metadataVersion2));
+ }
+ }
+
+ /**
+ * Parses a parquet metadata version string
+ */
+ public static class VersionParser {
--- End diff --
This an be extracted into separate class, there is no need to keep it as
inner.
If we create separate entity for parquet metadata version, we might include
parse method directly in that class.
> 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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