content: /*
   * 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.carbondata.core.index.dev;
  
  import java.io.IOException;
  import java.util.List;
  import java.util.Map;
  
  import org.apache.carbondata.common.annotations.InterfaceAudience;
  import org.apache.carbondata.core.datastore.block.SegmentProperties;
  import org.apache.carbondata.core.index.Segment;
  import org.apache.carbondata.core.indexstore.Blocklet;
  import org.apache.carbondata.core.indexstore.PartitionSpec;
  import org.apache.carbondata.core.metadata.schema.table.CarbonTable;
  import org.apache.carbondata.core.scan.expression.Expression;
  import org.apache.carbondata.core.scan.filter.executer.FilterExecutor;
  import org.apache.carbondata.core.scan.filter.resolver.FilterResolverIntf;
  
  /**
   * An entity which can store and retrieve index data.
   */
  @InterfaceAudience.Internal
  public interface Index<T extends Blocklet> {
  
    /**
     * It is called to load the index to memory or to initialize it.
     */
    void init(IndexModel indexModel) throws IOException;
  
    /**
     * Prune the table with resolved filter expression.
     * It returns the list of blocklets where these filters can exist.
     */
    List<T> prune(FilterResolverIntf filterExp, SegmentProperties segmentProperties,
        FilterExecutor filterExecutor, CarbonTable table) throws IOException;
  
    /**
     * Prune the table with filter expression. It returns the list of
     * blocklets where these filters can exist.
     */
    List<T> prune(Expression filter, SegmentProperties segmentProperties,
        CarbonTable carbonTable, FilterExecutor filterExecutor);
  
    /**
     * Prune the indexes for finding the row count. It returns a Map of
     * blocklet path and the row count
     */
    long getRowCount(Segment segment, List<PartitionSpec> partitions);
  
    /**
     * Prune the indexes for finding the row count for each block. It returns a Map of
     * blocklet path and the row count
     */
    Map<String, Long> getRowCountForEachBlock(Segment segment, List<PartitionSpec> partitions,
        Map<String, Long> blockletToRowCountMap);
  
    // TODO Move this method to Abstract class
    /**
     * Validate whether the current segment needs to be fetching the required data
     */
    boolean isScanRequired(FilterResolverIntf filterExp);
  
    /**
     * Validate Partition info, to check if any partitions is dropped
     */
    boolean validatePartitionInfo(List<PartitionSpec> partitions);
  
    /**
     * Clear complete index table and release memory.
     */
    void clear();
  
    /**
     * clears all the resources
     */
    void finish();
  
    /**
     * Returns number of records information that are stored in Index.
     * Driver multi-thread block pruning happens based on the number of rows in Index.
     * So Indexes can have multiple rows if they store information of multiple files.
     * so, this number of entries is used to represent how many files information a Index contains
     */
    int getNumberOfEntries();
  }
  