[GitHub] [iceberg] jackye1995 commented on a diff in pull request #6449: WIP: Delta: Adding support for Migrating Delta Lake Table to Iceberg Table

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

jackye1995 commented on code in PR #6449:
URL: https://github.com/apache/iceberg/pull/6449#discussion_r1063963541


##########
delta-lake/src/main/java/org/apache/iceberg/delta/DeltaLakeTypeToType.java:
##########
@@ -0,0 +1,158 @@
+/*
+ * 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.delta;
+
+import io.delta.standalone.types.ArrayType;
+import io.delta.standalone.types.BinaryType;
+import io.delta.standalone.types.BooleanType;
+import io.delta.standalone.types.ByteType;
+import io.delta.standalone.types.DataType;
+import io.delta.standalone.types.DateType;
+import io.delta.standalone.types.DecimalType;
+import io.delta.standalone.types.DoubleType;
+import io.delta.standalone.types.FloatType;
+import io.delta.standalone.types.IntegerType;
+import io.delta.standalone.types.LongType;
+import io.delta.standalone.types.MapType;
+import io.delta.standalone.types.ShortType;
+import io.delta.standalone.types.StringType;
+import io.delta.standalone.types.StructField;
+import io.delta.standalone.types.StructType;
+import io.delta.standalone.types.TimestampType;
+import java.util.List;
+import org.apache.iceberg.relocated.com.google.common.collect.Lists;
+import org.apache.iceberg.types.Type;
+import org.apache.iceberg.types.Types;
+
+class DeltaLakeTypeToType extends DeltaLakeDataTypeVisitor<Type> {
+  private final StructType root;
+  private int nextId = 0;
+
+  DeltaLakeTypeToType() {
+    this.root = null;
+  }
+
+  DeltaLakeTypeToType(StructType root) {
+    this.root = root;
+    this.nextId = root.getFields().length;
+  }
+
+  private int getNextId() {
+    int next = nextId;
+    nextId += 1;
+    return next;
+  }
+
+  @Override
+  @SuppressWarnings("ReferenceEquality")
+  public Type struct(StructType struct, List<Type> types) {
+    StructField[] fields = struct.getFields();
+    List<Types.NestedField> newFields = Lists.newArrayListWithExpectedSize(fields.length);
+    boolean isRoot = root == struct;
+    for (int i = 0; i < fields.length; i += 1) {
+      StructField field = fields[i];
+      Type type = types.get(i);
+
+      int id;
+      if (isRoot) {
+        // for new conversions, use ordinals for ids in the root struct
+        id = i;
+      } else {
+        id = getNextId();
+      }
+
+      // TODO: refactor const string
+      String doc =
+          field.getMetadata().contains("comment")
+              ? field.getMetadata().get("comment").toString()
+              : null;
+
+      if (field.isNullable()) {
+        newFields.add(Types.NestedField.optional(id, field.getName(), type, doc));
+      } else {
+        newFields.add(Types.NestedField.required(id, field.getName(), type, doc));
+      }
+    }
+
+    return Types.StructType.of(newFields);
+  }
+
+  @Override
+  public Type field(StructField field, Type typeResult) {
+    return typeResult;
+  }
+
+  @Override
+  public Type array(ArrayType array, Type elementType) {
+    if (array.containsNull()) {
+      return Types.ListType.ofOptional(getNextId(), elementType);
+    } else {
+      return Types.ListType.ofRequired(getNextId(), elementType);
+    }
+  }
+
+  @Override
+  public Type map(MapType map, Type keyType, Type valueType) {
+    if (map.valueContainsNull()) {
+      return Types.MapType.ofOptional(getNextId(), getNextId(), keyType, valueType);
+    } else {
+      return Types.MapType.ofRequired(getNextId(), getNextId(), keyType, valueType);
+    }
+  }
+
+  @SuppressWarnings("checkstyle:CyclomaticComplexity")
+  @Override
+  public Type atomic(DataType atomic) {
+    // TODO: pay attention to Delta's NullType, currently unhandled
+    if (atomic instanceof BooleanType) {
+      return Types.BooleanType.get();
+
+    } else if (atomic instanceof IntegerType
+        || atomic instanceof ShortType
+        || atomic instanceof ByteType) {
+      return Types.IntegerType.get();
+
+    } else if (atomic instanceof LongType) {
+      return Types.LongType.get();
+
+    } else if (atomic instanceof FloatType) {
+      return Types.FloatType.get();
+
+    } else if (atomic instanceof DoubleType) {
+      return Types.DoubleType.get();
+
+    } else if (atomic instanceof StringType) {
+      return Types.StringType.get();
+
+    } else if (atomic instanceof DateType) {
+      return Types.DateType.get();
+
+    } else if (atomic instanceof TimestampType) {
+      return Types.TimestampType.withZone();
+
+    } else if (atomic instanceof DecimalType) {
+      return Types.DecimalType.of(
+          ((DecimalType) atomic).getPrecision(), ((DecimalType) atomic).getScale());
+    } else if (atomic instanceof BinaryType) {
+      return Types.BinaryType.get();
+    }
+
+    throw new UnsupportedOperationException("Not a supported type: " + atomic.getCatalogString());

Review Comment:
   this is not an unsupported operation but an unsupported type, so I think it should be a validation exception?



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