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/*
 * Copyright (c) 2019 Couchbase, Inc.
 *
 * Licensed 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 com.couchbase.columnar.client.java;

/**
 * The possible values for scan consistency in an columnar query.
 */
public enum ScanConsistency {

  /**
   * The index will return whatever state it has to the columnar query engine at the time of query.
   * 
   * This is the default (for single-statement requests). No timestamp vector is used in the index scan. This is also
   * the fastest mode, because we avoid the cost of obtaining the vector, and we also avoid any wait for the index
   * to catch up to the vector.
   */
  NOT_BOUNDED {
    @Override
    public String toString() {
      return "not_bounded";
    }
  },

  /**
   * The index will wait until all mutations have been processed at the time of request before being processed in the
   * columnar query engine.
   * 
   * This implements strong consistency per request. Before processing the request, a current vector is obtained.
   * The vector is used as a lower bound for the statements in the request.
   */
  REQUEST_PLUS {
    @Override
    public String toString() {
      return "request_plus";
    }
  }

}