code: /*
   * 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.skywalking.oap.server.core.storage.model;
  
  import java.util.ArrayList;
  import java.util.List;
  import lombok.Getter;
  import org.apache.skywalking.oap.server.library.util.CollectionUtils;
  
  /**
   * @since 9.0.0
   */
  @Getter
  public class SQLDatabaseExtension {
      private final List<MultiColumnsIndex> indices = new ArrayList<>(5);
  
      public void appendIndex(MultiColumnsIndex index) {
          indices.add(index);
      }
  
      /**
       * The multiple columns index if the storage could support this mode. Many NO-SQL support one column index only, in that
       * case, this could be ignored in the implementation level.
       */
      @Getter
      public static class MultiColumnsIndex {
          private String[] columns;
  
          public MultiColumnsIndex(String mainColumn, final String[] withColumns) {
              if (CollectionUtils.isNotEmpty(withColumns)) {
                  columns = new String[withColumns.length + 1];
                  columns[0] = mainColumn;
                  System.arraycopy(withColumns, 0, columns, 1, withColumns.length);
              } else {
                  throw new IllegalArgumentException("ExtraQueryIndex required withColumns as a not empty list.");
              }
  
          }
  
          /**
           * Keep the same name replacement as {@link ColumnName#overrideName(String, String)}
           *
           * @param oldName to be replaced.
           * @param newName to use in the storage level.
           */
          public void overrideName(String oldName, String newName) {
              for (int i = 0; i < columns.length; i++) {
                  if (columns[i].equals(oldName)) {
                      columns[i] = newName;
                  }
              }
          }
      }
  }
  