[GitHub] [spark] RussellSpitzer commented on a change in pull request #24246: [SPARK-24252][SQL] Add TableCatalog API

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RussellSpitzer commented on a change in pull request #24246: [SPARK-24252][SQL] Add TableCatalog API
URL: https://github.com/apache/spark/pull/24246#discussion_r281359337
 
 

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 File path: sql/catalyst/src/main/java/org/apache/spark/sql/catalog/v2/TableChange.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.spark.sql.catalog.v2;
+
+import org.apache.spark.sql.types.DataType;
+
+/**
+ * TableChange subclasses represent requested changes to a table. These are passed to
+ * {@link TableCatalog#alterTable}. For example,
+ * <pre>
+ *   import TableChange._
+ *   val catalog = Catalogs.load(name)
+ *   catalog.asTableCatalog.alterTable(ident,
+ *       addColumn("x", IntegerType),
+ *       renameColumn("a", "b"),
+ *       deleteColumn("c")
+ *     )
+ * </pre>
+ */
+public interface TableChange {
+
+  /**
+   * Create a TableChange for setting a table property.
+   * <p>
+   * If the property already exists, it will be replaced with the new value.
+   *
+   * @param property the property name
+   * @param value the new property value
+   * @return a TableChange for the addition
+   */
+  static TableChange setProperty(String property, String value) {
+    return new SetProperty(property, value);
+  }
+
+  /**
+   * Create a TableChange for removing a table property.
+   * <p>
+   * If the property does not exist, the change will succeed.
+   *
+   * @param property the property name
+   * @return a TableChange for the addition
+   */
+  static TableChange removeProperty(String property) {
+    return new RemoveProperty(property);
+  }
+
+  /**
+   * Create a TableChange for adding an optional column.
+   * <p>
+   * If the field already exists, the change will result in an {@link IllegalArgumentException}.
+   * If the new field is nested and its parent does not exist or is not a struct, the change will
+   * result in an {@link IllegalArgumentException}.
+   *
+   * @param fieldNames field names of the new column
+   * @param dataType the new column's data type
+   * @return a TableChange for the addition
+   */
+  static TableChange addColumn(String[] fieldNames, DataType dataType) {
+    return new AddColumn(fieldNames, dataType, true, null);
+  }
+
+  /**
+   * Create a TableChange for adding a column.
+   * <p>
+   * If the field already exists, the change will result in an {@link IllegalArgumentException}.
+   * If the new field is nested and its parent does not exist or is not a struct, the change will
+   * result in an {@link IllegalArgumentException}.
+   *
+   * @param fieldNames field names of the new column
+   * @param dataType the new column's data type
+   * @param isNullable whether the new column can contain null
+   * @return a TableChange for the addition
+   */
+  static TableChange addColumn(String[] fieldNames, DataType dataType, boolean isNullable) {
+    return new AddColumn(fieldNames, dataType, isNullable, null);
+  }
+
+  /**
+   * Create a TableChange for adding a column.
+   * <p>
+   * If the field already exists, the change will result in an {@link IllegalArgumentException}.
+   * If the new field is nested and its parent does not exist or is not a struct, the change will
+   * result in an {@link IllegalArgumentException}.
+   *
+   * @param fieldNames field names of the new column
+   * @param dataType the new column's data type
+   * @param isNullable whether the new column can contain null
+   * @param comment the new field's comment string
+   * @return a TableChange for the addition
+   */
+  static TableChange addColumn(
+      String[] fieldNames,
+      DataType dataType,
+      boolean isNullable,
+      String comment) {
+    return new AddColumn(fieldNames, dataType, isNullable, comment);
+  }
+
+  /**
+   * Create a TableChange for renaming a field.
+   * <p>
+   * The name is used to find the field to rename. The new name will replace the leaf field name.
+   * For example, renameColumn(["a", "b", "c"], "x") should produce column a.b.x.
+   * <p>
+   * If the field does not exist, the change will result in an {@link IllegalArgumentException}.
+   *
+   * @param fieldNames the current field names
+   * @param newName the new name
+   * @return a TableChange for the rename
+   */
+  static TableChange renameColumn(String[] fieldNames, String newName) {
+    return new RenameColumn(fieldNames, newName);
+  }
+
+  /**
+   * Create a TableChange for updating the type of a field that is nullable.
+   * <p>
+   * The field names are used to find the field to update.
+   * <p>
+   * If the field does not exist, the change will result in an {@link IllegalArgumentException}.
+   *
+   * @param fieldNames field names of the column to update
+   * @param newDataType the new data type
+   * @return a TableChange for the update
+   */
+  static TableChange updateColumn(String[] fieldNames, DataType newDataType) {
 
 Review comment:
   I think it's fine as is (since there are no other ways to "update" a column), if you were gonna change it I would go with updateColumnType anyway

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