standalone-metastore/metastore-common/src/main/java/org/apache/hadoop/hive/metastore/HiveMetaHook.java

/*
 * 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.hadoop.hive.metastore;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.hive.metastore.api.EnvironmentContext;
import org.apache.hadoop.hive.metastore.api.MetaException;
import org.apache.hadoop.hive.metastore.api.Table;

import com.google.common.collect.ImmutableList;

import java.util.List;

/**
 * HiveMetaHook defines notification methods which are invoked as part
 * of transactions against the metastore, allowing external catalogs
 * such as HBase to be kept in sync with Hive's metastore.
 *
 *<p>
 *
 * Implementations can use {@link org.apache.hadoop.hive.metastore.utils.MetaStoreUtils#isExternalTable} to
 * distinguish external tables from managed tables.
 */
@InterfaceAudience.Public
@InterfaceStability.Stable
public interface HiveMetaHook {

  public String ALTER_TABLE_OPERATION_TYPE = "alterTableOpType";

  // These should remain in sync with AlterTableType enum
  public List<String> allowedAlterTypes = ImmutableList.of("ADDPROPS", "DROPPROPS");
  String ALTERLOCATION = "ALTERLOCATION";

  /**
   * Called before a new table definition is added to the metastore
   * during CREATE TABLE.
   *
   * @param table new table definition
   */
  public void preCreateTable(Table table)
    throws MetaException;

  /**
   * Called after failure adding a new table definition to the metastore
   * during CREATE TABLE.
   *
   * @param table new table definition
   */
  public void rollbackCreateTable(Table table)
    throws MetaException;

  /**
   * Called after successfully adding a new table definition to the metastore
   * during CREATE TABLE.
   *
   * @param table new table definition
   */
  public void commitCreateTable(Table table)
    throws MetaException;

  /**
   * Called before a table definition is removed from the metastore
   * during DROP TABLE.
   *
   * @param table table definition
   */
  public void preDropTable(Table table)
    throws MetaException;

  /**
   * Called after failure removing a table definition from the metastore
   * during DROP TABLE.
   *
   * @param table table definition
   */
  public void rollbackDropTable(Table table)
    throws MetaException;

  /**
   * Called after successfully removing a table definition from the metastore
   * during DROP TABLE.
   *
   * @param table table definition
   *
   * @param deleteData whether to delete data as well; this should typically
   * be ignored in the case of an external table
   */
  public void commitDropTable(Table table, boolean deleteData)
    throws MetaException;

  /**
   * Called before a table is altered in the metastore
   * during ALTER TABLE.
   *
   * @param table new table definition
   */
  public default void preAlterTable(Table table, EnvironmentContext context) throws MetaException {
    String alterOpType = (context == null || context.getProperties() == null) ?
        null : context.getProperties().get(ALTER_TABLE_OPERATION_TYPE);
    // By default allow only ADDPROPS and DROPPROPS.
    // alterOpType is null in case of stats update.
    if (alterOpType != null && !allowedAlterTypes.contains(alterOpType)){
      throw new MetaException(
          "ALTER TABLE can not be used for " + alterOpType + " to a non-native table ");
    }
  }

}