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.calcite.plan;
  
  import java.math.BigDecimal;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * RelOptSamplingParameters represents the parameters necessary to produce a
   * sample of a relation.
   *
   * <p>Its parameters are derived from the SQL 2003 TABLESAMPLE clause.
   */
  public class RelOptSamplingParameters {
    //~ Instance fields --------------------------------------------------------
  
    private final boolean bernoulli;
    public final BigDecimal sampleRate;
    private final boolean repeatable;
    private final int repeatableSeed;
  
    //~ Constructors -----------------------------------------------------------
  
    public RelOptSamplingParameters(boolean bernoulli, BigDecimal sampleRate,
        boolean repeatable, int repeatableSeed) {
      this.bernoulli = bernoulli;
      this.sampleRate = requireNonNull(sampleRate, "sampleRate");
      this.repeatable = repeatable;
      this.repeatableSeed = repeatableSeed;
    }
  
    @Deprecated // to be removed before 2.0
    public RelOptSamplingParameters(
        boolean bernoulli,
        float sampleRate,
        boolean isRepeatable,
        int repeatableSeed) {
      this(bernoulli, BigDecimal.valueOf(sampleRate), isRepeatable,
          repeatableSeed);
    }
  
    //~ Methods ----------------------------------------------------------------
  
    /**
     * Indicates whether Bernoulli or system sampling should be performed.
     * Bernoulli sampling requires the decision whether to include each row in
     * the sample to be independent across rows. System sampling allows
     * implementation-dependent behavior.
     *
     * @return true if Bernoulli sampling is configured, false for system
     * sampling
     */
    public boolean isBernoulli() {
      return bernoulli;
    }
  
    /**
     * Returns the sampling percentage. For Bernoulli sampling, the sampling
     * percentage is the likelihood that any given row will be included in the
     * sample. For system sampling, the sampling percentage indicates (roughly)
     * what percentage of the rows will appear in the sample.
     *
     * @return the sampling percentage between 0.0 and 1.0, exclusive
     */
    @Deprecated // to be removed before 2.0
    public float getSamplingPercentage() {
      return sampleRate.floatValue();
    }
  
    /**
     * Indicates whether the sample results should be repeatable. Sample results
     * are only required to repeat if no changes have been made to the
     * relation's content or structure. If the sample is configured to be
     * repeatable, then a user-specified seed value can be obtained via
     * {@link #getRepeatableSeed()}.
     *
     * @return true if the sample results should be repeatable
     */
    public boolean isRepeatable() {
      return repeatable;
    }
  
    /**
     * If {@link #isRepeatable()} returns <code>true</code>, this method returns a
     * user-specified seed value. Samples of the same, unmodified relation
     * should be identical if the sampling mode, sampling percentage and
     * repeatable seed are the same.
     *
     * @return seed value for repeatable samples
     */
    public int getRepeatableSeed() {
      return repeatableSeed;
    }
  }
  