[GitHub] [iceberg] chenjunjiedada commented on a change in pull request #1352: Support row-level deletes with IcebergGenerics

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

chenjunjiedada commented on a change in pull request #1352:
URL: https://github.com/apache/iceberg/pull/1352#discussion_r474541698



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File path: data/src/main/java/org/apache/iceberg/data/GenericReader.java
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@@ -0,0 +1,292 @@
+/*
+ * 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.data;
+
+import java.io.Serializable;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.function.Function;
+import org.apache.iceberg.Accessor;
+import org.apache.iceberg.CombinedScanTask;
+import org.apache.iceberg.DataFile;
+import org.apache.iceberg.DeleteFile;
+import org.apache.iceberg.FileContent;
+import org.apache.iceberg.FileScanTask;
+import org.apache.iceberg.MetadataColumns;
+import org.apache.iceberg.Schema;
+import org.apache.iceberg.StructLike;
+import org.apache.iceberg.TableScan;
+import org.apache.iceberg.avro.Avro;
+import org.apache.iceberg.data.avro.DataReader;
+import org.apache.iceberg.data.orc.GenericOrcReader;
+import org.apache.iceberg.data.parquet.GenericParquetReaders;
+import org.apache.iceberg.deletes.Deletes;
+import org.apache.iceberg.expressions.Evaluator;
+import org.apache.iceberg.expressions.Expression;
+import org.apache.iceberg.expressions.Expressions;
+import org.apache.iceberg.io.CloseableGroup;
+import org.apache.iceberg.io.CloseableIterable;
+import org.apache.iceberg.io.CloseableIterator;
+import org.apache.iceberg.io.FileIO;
+import org.apache.iceberg.io.InputFile;
+import org.apache.iceberg.orc.ORC;
+import org.apache.iceberg.parquet.Parquet;
+import org.apache.iceberg.relocated.com.google.common.collect.Iterables;
+import org.apache.iceberg.relocated.com.google.common.collect.Lists;
+import org.apache.iceberg.relocated.com.google.common.collect.Maps;
+import org.apache.iceberg.relocated.com.google.common.collect.Multimap;
+import org.apache.iceberg.relocated.com.google.common.collect.Multimaps;
+import org.apache.iceberg.relocated.com.google.common.collect.Sets;
+import org.apache.iceberg.types.TypeUtil;
+import org.apache.iceberg.types.Types;
+import org.apache.iceberg.util.PartitionUtil;
+import org.apache.iceberg.util.ProjectStructLike;
+import org.apache.iceberg.util.StructLikeSet;
+
+class GenericReader implements Serializable {
+  private static final Schema POS_DELETE_SCHEMA = new Schema(
+      MetadataColumns.DELETE_FILE_PATH,
+      MetadataColumns.DELETE_FILE_POS);
+
+  private final FileIO io;
+  private final Schema projection;
+  private final boolean caseSensitive;
+  private final boolean reuseContainers;
+
+  GenericReader(TableScan scan, boolean reuseContainers) {
+    this.io = scan.table().io();
+    this.projection = scan.schema();
+    this.caseSensitive = scan.isCaseSensitive();
+    this.reuseContainers = reuseContainers;
+  }
+
+  CloseableIterator<Record> open(CloseableIterable<CombinedScanTask> tasks) {
+    Iterable<FileScanTask> fileTasks = Iterables.concat(Iterables.transform(tasks, CombinedScanTask::files));
+    return CloseableIterable.concat(Iterables.transform(fileTasks, this::open)).iterator();
+  }
+
+  public CloseableIterable<Record> open(CombinedScanTask task) {
+    return new CombinedTaskIterable(task);
+  }
+
+  public CloseableIterable<Record> open(FileScanTask task) {
+    List<DeleteFile> posDeletes = Lists.newArrayList();
+    List<DeleteFile> eqDeletes = Lists.newArrayList();
+    for (DeleteFile delete : task.deletes()) {
+      switch (delete.content()) {
+        case POSITION_DELETES:
+          posDeletes.add(delete);
+          break;
+        case EQUALITY_DELETES:
+          eqDeletes.add(delete);
+          break;
+        default:
+          throw new UnsupportedOperationException("Unknown delete file content: " + delete.content());
+      }
+    }
+
+    Schema fileProjection = fileProjection(!posDeletes.isEmpty());
+
+    CloseableIterable<Record> records = openFile(task, fileProjection);
+    records = applyPosDeletes(records, fileProjection, task.file().path(), posDeletes, task.file());
+    records = applyEqDeletes(records, fileProjection, eqDeletes, task.file());
+    records = applyResidual(records, fileProjection, task.residual());
+
+    return records;
+  }
+
+  private Schema fileProjection(boolean hasPosDeletes) {
+    if (hasPosDeletes) {
+      List<Types.NestedField> columns = Lists.newArrayList(projection.columns());
+      columns.add(MetadataColumns.ROW_POSITION);
+      return new Schema(columns);
+    }
+
+    return projection;
+  }
+
+  private CloseableIterable<Record> applyResidual(CloseableIterable<Record> records, Schema recordSchema,
+                                                  Expression residual) {
+    if (residual != null && residual != Expressions.alwaysTrue()) {
+      InternalRecordWrapper wrapper = new InternalRecordWrapper(recordSchema.asStruct());
+      Evaluator filter = new Evaluator(recordSchema.asStruct(), residual, caseSensitive);
+      return CloseableIterable.filter(records, record -> filter.eval(wrapper.wrap(record)));
+    }
+
+    return records;
+  }
+
+  private CloseableIterable<Record> applyEqDeletes(CloseableIterable<Record> records, Schema recordSchema,
+                                                   List<DeleteFile> eqDeletes, DataFile dataFile) {
+    if (eqDeletes.isEmpty()) {
+      return records;
+    }
+
+    Multimap<Set<Integer>, DeleteFile> filesByDeleteIds = Multimaps.newMultimap(Maps.newHashMap(), Lists::newArrayList);
+    for (DeleteFile delete : eqDeletes) {
+      filesByDeleteIds.put(Sets.newHashSet(delete.equalityFieldIds()), delete);
+    }
+
+    CloseableIterable<Record> filteredRecords = records;
+    for (Map.Entry<Set<Integer>, Collection<DeleteFile>> entry : filesByDeleteIds.asMap().entrySet()) {
+      Set<Integer> ids = entry.getKey();
+      Iterable<DeleteFile> deletes = entry.getValue();
+
+      Schema deleteSchema = TypeUtil.select(recordSchema, ids);
+      int[] orderedIds = deleteSchema.columns().stream().mapToInt(Types.NestedField::fieldId).toArray();
+
+      // a wrapper to translate from generic objects to internal representations
+      InternalRecordWrapper asStructLike = new InternalRecordWrapper(recordSchema.asStruct());
+
+      // a projection to select and reorder fields of the file schema to match the delete rows
+      ProjectStructLike projectRow = ProjectStructLike.of(recordSchema, orderedIds);
+
+      Iterable<CloseableIterable<Record>> deleteRecords = Iterables.transform(deletes,
+          delete -> openDeletes(delete, dataFile, deleteSchema));
+      StructLikeSet deleteSet = Deletes.toEqualitySet(
+          // copy the delete records because they will be held in a set
+          CloseableIterable.transform(CloseableIterable.concat(deleteRecords), Record::copy),
+          deleteSchema.asStruct());
+
+      filteredRecords = Deletes.filter(filteredRecords,
+          record -> projectRow.wrap(asStructLike.wrap(record)), deleteSet);
+    }
+
+    return filteredRecords;
+  }
+
+  private CloseableIterable<Record> applyPosDeletes(CloseableIterable<Record> records, Schema recordSchema,
+                                                    CharSequence file, List<DeleteFile> posDeletes, DataFile dataFile) {
+    if (posDeletes.isEmpty()) {
+      return records;
+    }
+
+    Accessor<StructLike> posAccessor = recordSchema.accessorForField(MetadataColumns.ROW_POSITION.fieldId());
+    Function<Record, Long> posGetter = record -> (Long) posAccessor.get(record);
+    List<CloseableIterable<StructLike>> deletes = Lists.transform(posDeletes,
+        delete -> openPosDeletes(delete, dataFile));
+
+    // if there are fewer deletes than a reasonable number to keep in memory, use a set
+    if (posDeletes.stream().mapToLong(DeleteFile::recordCount).sum() < 100_000L) {

Review comment:
       Can we make this configurable? For example, let users choose how much memory they want to use for this.




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