metastore/metastore-api/src/main/java/org/apache/drill/metastore/statistics/StatisticsKind.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.drill.metastore.statistics;

import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.annotation.JsonGetter;
import com.fasterxml.jackson.annotation.JsonInclude;

/**
 * Class represents kind of statistics or metadata, for example it may be min value for column,
 * or row count for table.
 */
@JsonInclude(JsonInclude.Include.NON_DEFAULT)
@JsonFormat(shape = JsonFormat.Shape.OBJECT)
public interface StatisticsKind<T> {

  /**
   * Returns name which corresponds to the statistics.
   *
   * @return statistic kind name
   */
  @JsonGetter(value = "name")
  String getName();

  @JsonGetter(value = "exact")
  default boolean isExact() {
    return false;
  }
}