[GitHub] [incubator-iceberg] rdblue commented on a change in pull request #933: [WIP] Mapred input format

[GitBox <gi...@apache.org>]

rdblue commented on a change in pull request #933:
URL: https://github.com/apache/incubator-iceberg/pull/933#discussion_r411555674



##########
File path: mr/src/main/java/org/apache/iceberg/mr/mapred/IcebergInputFormat.java
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@@ -0,0 +1,259 @@
+/*
+ * 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
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 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.iceberg.mr.mapred;
+
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.util.Iterator;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.StreamSupport;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.hive.ql.io.CombineHiveInputFormat;
+import org.apache.hadoop.mapred.FileSplit;
+import org.apache.hadoop.mapred.InputFormat;
+import org.apache.hadoop.mapred.InputSplit;
+import org.apache.hadoop.mapred.JobConf;
+import org.apache.hadoop.mapred.RecordReader;
+import org.apache.hadoop.mapred.Reporter;
+import org.apache.iceberg.CombinedScanTask;
+import org.apache.iceberg.DataFile;
+import org.apache.iceberg.FileScanTask;
+import org.apache.iceberg.Schema;
+import org.apache.iceberg.Table;
+import org.apache.iceberg.data.Record;
+import org.apache.iceberg.hadoop.HadoopInputFile;
+import org.apache.iceberg.hadoop.HadoopTables;
+import org.apache.iceberg.io.CloseableIterable;
+import org.apache.iceberg.io.InputFile;
+import org.apache.iceberg.mr.SerializationUtil;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * CombineHiveInputFormat.AvoidSplitCombination is implemented to correctly delegate InputSplit
+ * creation to this class. See: https://stackoverflow.com/questions/29133275/
+ * custom-inputformat-getsplits-never-called-in-hive
+ */
+public class IcebergInputFormat<T> implements InputFormat<Void, T>, CombineHiveInputFormat.AvoidSplitCombination {

Review comment:
       I doubt anyone would use the mapred format, so I think it makes sense to only add a `HiveInputFormat`.
   
   I'm not sure we want to add it to `iceberg-hive`, unless we don't add many dependencies. Right now, that module is for interacting with the Hive metastore so it is used in Spark and other places. If we don't need additional dependencies then having a `HiveInputFormat` class makes sense. But if we need to make that module pull in more, then we should consider a separate module for Hive integration.




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