[GitHub] [hive] vihangk1 commented on a change in pull request #2336: HIVE-24987: Introduce a exception list to skip incompatible column change check

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

vihangk1 commented on a change in pull request #2336:
URL: https://github.com/apache/hive/pull/2336#discussion_r643416465



##########
File path: standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/DefaultIncompatibleTableChangeHandler.java
##########
@@ -0,0 +1,116 @@
+/*
+ * 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
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.hadoop.hive.metastore;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hive.metastore.api.FieldSchema;
+import org.apache.hadoop.hive.metastore.api.InvalidOperationException;
+import org.apache.hadoop.hive.metastore.api.SerDeInfo;
+import org.apache.hadoop.hive.metastore.api.Table;
+import org.apache.hadoop.hive.metastore.conf.MetastoreConf;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Default incompatible table change handler. This is invoked by the {@link
+ * HiveAlterHandler} when a table is altered to check if the column type changes if any
+ * are allowed or not.
+ */
+public class DefaultIncompatibleTableChangeHandler implements
+    IMetaStoreIncompatibleChangeHandler {
+
+  private static final Logger LOG = LoggerFactory
+      .getLogger(DefaultIncompatibleTableChangeHandler.class);
+  private static final DefaultIncompatibleTableChangeHandler INSTANCE =
+      new DefaultIncompatibleTableChangeHandler();
+
+  private DefaultIncompatibleTableChangeHandler() {
+  }
+
+  public static DefaultIncompatibleTableChangeHandler get() {
+    return INSTANCE;
+  }
+
+  /**
+   * Checks if the column type changes in the oldTable and newTable are allowed or not. In
+   * addition to checking if the incompatible changes are allowed or not, this also checks
+   * if the table serde library belongs to a list of table serdes which support making any
+   * column type changes.
+   *
+   * @param conf     The configuration which if incompatible col type changes are allowed
+   *                 or not.
+   * @param oldTable The instance of the table being altered.
+   * @param newTable The new instance of the table which represents the altered state of
+   *                 the table.
+   * @throws InvalidOperationException
+   */
+  @Override
+  public void allowChange(Configuration conf, Table oldTable, Table newTable)
+      throws InvalidOperationException {
+    if (!MetastoreConf.getBoolVar(conf,
+        MetastoreConf.ConfVars.DISALLOW_INCOMPATIBLE_COL_TYPE_CHANGES)) {
+      // incompatible column changes are allowed for all
+      return;
+    }
+    if (oldTable.getTableType().equals(TableType.VIRTUAL_VIEW.toString())) {
+      // Views derive the column type from the base table definition. So the view
+      // definition can be altered to change the column types. The column type
+      // compatibility checks should be done only for non-views.
+      return;
+    }
+    checkColTypeChangeCompatible(conf, oldTable, newTable);
+  }
+
+  private void checkColTypeChangeCompatible(Configuration conf, Table oldTable,

Review comment:
       Yes, agreed. This was left here because of git conflicts. Thanks for spotting that.




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