Page History

package org.apache.kafka.streams.query;

/**
 * Interactive query for retrieving a set of records with the same specified key and different timestamps within the specified time range.
 */
@Evolving
public final class MultiVersionedKeyQuery<K, V> implements Query<ValueIterator<VersionedRecord<V>>> {

  private final K key;
  private final Optional<Instant> fromTimestamp;
  private final Optional<Instant> asOfTimestamp;
  private final boolean isAscending;

  private MultiVersionedKeyQuery(
      final K key,
      Optional<Instant> fromTimestamp,
      Optional<Instant> asOfTimestamp,
      boolean isAscending) {
    this.key = Objects.requireNonNull(key);
    this.fromTimestamp = fromTimestamp;
    this.asOfTimestamp = asOfTimestamp;
    this.isAscending = isAscending;
  }

  /**
   * Creates a query that will retrieve the set of records identified by {@code key} if any exists
   * (or {@code null} otherwise).
   * @param key The key to retrieve
   * @throws NullPointerException if @param key is null           
   * @param <K> The type of the key
   * @param <V> The type of the value that will be retrieved
   */
  public static <K, V> MultiVersionedKeyQuery<K, V> withKey(final K key);

  /**
   * Specifies the starting time point for the key query.
   * <pre>
   * The key query returns all the records that are still validexisting in the time range starting from the timestamp {@code fromTimestamp}. There can be records which have been inserted before the {@code fromTimestamp} 
   * and are valid in the query specified time range (the whole time range or even partially). The key query in fact returns all the records that have NOT became tombstone at or after {@code fromTimestamp}.  
   * </pre>  
   * @param fromTimestamp The starting time point
   * @throws NullPointerException if @param fromTimestamp is null  
   */
  public MultiVersionedKeyQuery<K, V> from(Instant fromTimestamp);

  /**
   * Specifies the ending time point for the key query.
   * The key query returns all the records that have timestamp <= {@code asOfTimestamp}.
   * @param asOfTimestamp The ending time point
   * @throws NullPointerException if @param asOfTimestamp is null  
  */
  public MultiVersionedKeyQuery<K, V> asOf(Instant asOfTimestamp);

  /**
   * Specifies the starting and ending points of the key query as MIN and MAX respectively.
   * Therefore, the query returns all the existing records in the state store with the specified key.
   * @throws RuntimeException if {@code fromTimestamp} or {@code asOfTimestamp} have been already
   * specified.
   */
  public MultiVersionedKeyQuery<K, V> allVersions();

  /**
   * Specifies the order of the returned records by the query as descending by timestamp.
   */
  public MultiVersionedKeyQuery<K, V> withDescendingTimestamps();

  /**
   * The key that was specified for this query.
   */
  public K key();

  /**
   * The starting time point of the query, if specified
   */
  public Optional<Instant> fromTimestamp();

  /**
   * The ending time point of the query, if specified
   */
  public Optional<Instant> asOfTimestamp();

  /**
   * @return true if the query returns records in ascending order of timestamps
   */
  public boolean isAscending ();
}