[GitHub] [incubator-iceberg] edgarRd commented on a change in pull request #227: ORC column map fix

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

edgarRd commented on a change in pull request #227: ORC column map fix
URL: https://github.com/apache/incubator-iceberg/pull/227#discussion_r333739073
 
 

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 File path: orc/src/main/java/org/apache/iceberg/orc/ORCSchemaUtil.java
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+/*
+ * 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.orc;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Lists;
+import com.google.common.collect.Maps;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.concurrent.atomic.AtomicInteger;
+import org.apache.iceberg.Schema;
+import org.apache.iceberg.types.Type;
+import org.apache.iceberg.types.TypeUtil;
+import org.apache.iceberg.types.Types;
+import org.apache.orc.TypeDescription;
+
+/**
+ * Utilities for mapping Iceberg to ORC schemas.
+ */
+final class ORCSchemaUtil {
+
+  private static final String ICEBERG_ID_ATTRIBUTE = "iceberg.id";
+  private static final String ICEBERG_REQUIRED_ATTRIBUTE = "iceberg.required";
+
+  private static final Map<Type.TypeID, TypeDescription.Category> TYPE_MAPPING =
+      ImmutableMap.<Type.TypeID, TypeDescription.Category>builder()
+          .put(Type.TypeID.BOOLEAN, TypeDescription.Category.BOOLEAN)
+          .put(Type.TypeID.INTEGER, TypeDescription.Category.INT)
+          .put(Type.TypeID.TIME, TypeDescription.Category.INT)
+          .put(Type.TypeID.LONG, TypeDescription.Category.LONG)
+          .put(Type.TypeID.FLOAT, TypeDescription.Category.FLOAT)
+          .put(Type.TypeID.DOUBLE, TypeDescription.Category.DOUBLE)
+          .put(Type.TypeID.DATE, TypeDescription.Category.DATE)
+          .put(Type.TypeID.TIMESTAMP, TypeDescription.Category.TIMESTAMP)
+          .put(Type.TypeID.STRING, TypeDescription.Category.STRING)
+          .put(Type.TypeID.UUID, TypeDescription.Category.BINARY)
+          .put(Type.TypeID.FIXED, TypeDescription.Category.BINARY)
+          .put(Type.TypeID.BINARY, TypeDescription.Category.BINARY)
+          .put(Type.TypeID.DECIMAL, TypeDescription.Category.DECIMAL)
+          .build();
+
+  private ORCSchemaUtil() {}
+
+  static TypeDescription toOrc(Schema schema) {
+    final TypeDescription root = TypeDescription.createStruct();
+    final Types.StructType schemaRoot = schema.asStruct();
+    for (Types.NestedField field : schemaRoot.asStructType().fields()) {
+      TypeDescription orcColumType = toOrc(field.fieldId(), field.type(), field.isRequired());
+      root.addField(field.name(), orcColumType);
+    }
+    return root;
+  }
+
+  private static TypeDescription toOrc(Integer fieldId, Type type, boolean isRequired) {
+    final TypeDescription orcType;
+
+    switch (type.typeId()) {
+      case BOOLEAN:
+        orcType = TypeDescription.createBoolean();
+        break;
+      case INTEGER:
+      case TIME:
+        orcType = TypeDescription.createInt();
+        break;
+      case LONG:
+        orcType = TypeDescription.createLong();
+        break;
+      case FLOAT:
+        orcType = TypeDescription.createFloat();
+        break;
+      case DOUBLE:
+        orcType = TypeDescription.createDouble();
+        break;
+      case DATE:
+        orcType = TypeDescription.createDate();
+        break;
+      case TIMESTAMP:
+        orcType = TypeDescription.createTimestamp();
+        break;
+      case STRING:
+        orcType = TypeDescription.createString();
+        break;
+      case UUID:
+      case FIXED:
+      case BINARY:
+        orcType = TypeDescription.createBinary();
+        break;
+      case DECIMAL: {
+        Types.DecimalType decimal = (Types.DecimalType) type;
+        orcType = TypeDescription.createDecimal()
+            .withScale(decimal.scale())
+            .withPrecision(decimal.precision());
+        break;
+      }
+      case STRUCT: {
+        orcType = TypeDescription.createStruct();
+        for (Types.NestedField field : type.asStructType().fields()) {
+          TypeDescription childType = toOrc(field.fieldId(), field.type(), field.isRequired());
+          orcType.addField(field.name(), childType);
+        }
+        break;
+      }
+      case LIST: {
+        Types.ListType list = (Types.ListType) type;
+        TypeDescription elementType = toOrc(list.elementId(), list.elementType(),
+            list.isElementRequired());
+        orcType = TypeDescription.createList(elementType);
+        break;
+      }
+      case MAP: {
+        Types.MapType map = (Types.MapType) type;
+        TypeDescription keyType = toOrc(map.keyId(), map.keyType(), true);
+        TypeDescription valueType = toOrc(map.valueId(), map.valueType(), map.isValueRequired());
+        orcType = TypeDescription.createMap(keyType, valueType);
+        break;
+      }
+      default:
+        throw new IllegalArgumentException("Unhandled type " + type.typeId());
+    }
+
+    // Set Iceberg column attributes for mapping
+    orcType.setAttribute(ICEBERG_ID_ATTRIBUTE, String.valueOf(fieldId));
+    orcType.setAttribute(ICEBERG_REQUIRED_ATTRIBUTE, String.valueOf(isRequired));
+    return orcType;
+  }
+
+  /**
+   * Converts an Iceberg schema to a corresponding ORC schema within the context of an existing
 
 Review comment:
   The logic here is basically what http://iceberg.apache.org/spec/#orc describes in terms of schema evolution rules, I can add that to the comments.

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