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A module that is everything required to understands Druid Segments

There is a newer version: 0.12.3

/*
 * Licensed to Metamarkets Group Inc. (Metamarkets) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. Metamarkets 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 io.druid.segment;

import io.druid.segment.column.ColumnCapabilities;
import io.druid.segment.data.Indexed;
import org.joda.time.DateTime;
import org.joda.time.Interval;

/**
 */
public interface StorageAdapter extends CursorFactory
{
  public String getSegmentIdentifier();
  public Interval getInterval();
  public Indexed getAvailableDimensions();
  public Iterable getAvailableMetrics();

  /**
   * Returns the number of distinct values for the given dimension column
   * For dimensions of unknown cardinality, e.g. __time this currently returns
   * Integer.MAX_VALUE
   *
   * @param column
   * @return
   */
  public int getDimensionCardinality(String column);
  public DateTime getMinTime();
  public DateTime getMaxTime();
  public Capabilities getCapabilities();
  public ColumnCapabilities getColumnCapabilities(String column);

  /**
   * Like {@link ColumnCapabilities#getType()}, but may return a more descriptive string for complex columns.
   * @param column column name
   * @return type name
   */
  public String getColumnTypeName(String column);
  public int getNumRows();
  public DateTime getMaxIngestedEventTime();
  public Metadata getMetadata();
}