integration/spark/src/main/scala/org/apache/spark/sql/secondaryindex/util/IndexTableUtil.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.spark.sql.secondaryindex.util;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.apache.spark.sql.secondaryindex.exception.IndexTableExistException;
import org.apache.carbondata.core.metadata.schema.indextable.IndexTableInfo;

public class IndexTableUtil {
  /**
   * adds index table info into parent table properties
   *
   */
  public static String checkAndAddIndexTable(String gsonData, IndexTableInfo newIndexTable)
      throws IndexTableExistException {
    IndexTableInfo[] indexTableInfos = IndexTableInfo.fromGson(gsonData);
    if (null == indexTableInfos) {
      indexTableInfos = new IndexTableInfo[0];
    }
    List<IndexTableInfo> indexTables =
        new ArrayList<>(Arrays.asList(indexTableInfos));
    for (IndexTableInfo indexTable : indexTableInfos) {
      if (indexTable.getIndexCols().size() == newIndexTable.getIndexCols().size()) {
        //If column order is not same, then also index table creation should be successful
        //eg., index1 is a,b,d and index2 is a,d,b. Both table creation should be successful
        boolean isColumnOrderSame = true;
        for (int i = 0; i < indexTable.getIndexCols().size(); i++) {
          if (!indexTable.getIndexCols().get(i)
              .equalsIgnoreCase(newIndexTable.getIndexCols().get(i))) {
            isColumnOrderSame = false;
            break;
          }
        }
        if (isColumnOrderSame) {
          throw new IndexTableExistException("Index Table with selected columns already exist");
        }
      }
    }
    indexTables.add(newIndexTable);
    return IndexTableInfo.toGson(indexTables.toArray(new IndexTableInfo[0]));
  }
}