rdblue commented on a change in pull request #1972: URL: https://github.com/apache/iceberg/pull/1972#discussion_r550268330
########## File path: beam/src/main/java/org/apache/iceberg/beam/IcebergIO.java ########## @@ -0,0 +1,119 @@ +/* + * 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.beam; + +import org.apache.beam.sdk.io.WriteFilesResult; +import org.apache.beam.sdk.transforms.Combine; +import org.apache.beam.sdk.values.KV; +import org.apache.hadoop.conf.Configuration; +import org.apache.iceberg.AppendFiles; +import org.apache.iceberg.DataFiles; +import org.apache.iceberg.Schema; +import org.apache.iceberg.Snapshot; +import org.apache.iceberg.Table; +import org.apache.iceberg.catalog.TableIdentifier; +import org.apache.iceberg.exceptions.NoSuchTableException; +import org.apache.iceberg.hive.HiveCatalog; +import org.apache.iceberg.relocated.com.google.common.collect.ImmutableList; +import org.apache.iceberg.relocated.com.google.common.collect.Iterables; + +import java.util.LinkedList; +import java.util.List; + + +public class IcebergIO { + + private IcebergIO() { + } + + static void write(TableIdentifier table, + Schema schema, + String hiveMetastoreUrl, + WriteFilesResult<Void> resultFiles) { + resultFiles.getPerDestinationOutputFilenames().apply( + Combine.globally(new FileCombiner(table, schema, hiveMetastoreUrl)).withoutDefaults() + ); + } + + private static class FileCombiner extends Combine.CombineFn<KV<Void, String>, List<String>, Snapshot> { + private final TableIdentifier tableIdentifier; + private final Schema schema; + private final String hiveMetastoreUrl; + + FileCombiner(TableIdentifier table, Schema schema, String hiveMetastoreUrl) { + this.tableIdentifier = table; + this.schema = schema; + this.hiveMetastoreUrl = hiveMetastoreUrl; + } + + @Override + public List<String> createAccumulator() { + return new LinkedList<>(); + } + + @Override + public List<String> addInput(List<String> mutableAccumulator, KV<Void, String> input) { + mutableAccumulator.add(input.getValue()); + return mutableAccumulator; + } + + @Override + public List<String> mergeAccumulators(Iterable<List<String>> accumulators) { + return ImmutableList.copyOf(Iterables.concat(accumulators)); + } + + @Override + public Snapshot extractOutput(List<String> accumulator) { + try (HiveCatalog catalog = new HiveCatalog( + HiveCatalog.DEFAULT_NAME, + this.hiveMetastoreUrl, + 1, + new Configuration() + )) { + Table table; + try { + table = catalog.loadTable(this.tableIdentifier); + } catch (NoSuchTableException e) { + // If it doesn't exist, we just create the table + table = catalog.createTable(this.tableIdentifier, schema); + } + + // In case the schema has changed + if (table.schema() != this.schema) { + table.updateSchema().unionByNameWith(this.schema).commit(); + } + + // Append the new files + final AppendFiles app = table.newAppend(); + // We need to get the statistics, not easy to get them through Beam Review comment: Iceberg provides common write classes in the core module that we extend for Flink and Spark object models, so if you do go with Iceberg writers, it would probably not be too much code. For example, take a look at the [`SparkPartitionedWriter`](https://github.com/apache/iceberg/blob/master/spark/src/main/java/org/apache/iceberg/spark/source/SparkPartitionedWriter.java). Using Iceberg writers would help with stats as well as writing delete files if you later want to support CDC or other row-level use cases. But, one challenge is integrating those writers with an object model. Spark and Flink have row classes that are directly supported in the integration. It looks like you're using Avro generics for Avro, and using an object model specific to a data format is going to be a little difficult because Iceberg needs additional metadata, like field IDs. It sounds difficult to make sure that each format writer is producing the right information for Iceberg tables. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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