Class ColumnPrefixFilter

src/ColumnPrefixFilter.java:43–97

Sets a binary prefix to filter results based on the column qualifier. Efficiently compares the column qualifier bytes up to the length of the prefix to see if it matches. Only setting this filter will return all rows that match the criteria but at the same will cost a full table scan. @since

 * @since 1.5
 */
public final class ColumnPrefixFilter extends ScanFilter {

  private static final byte[] NAME = Bytes.ISO88591("org.apache.hadoop"
      + ".hbase.filter.ColumnPrefixFilter");

  private final byte[] prefix;

  /**
   * Constructor for a UTF-8 prefix string.
   */
  public ColumnPrefixFilter(final String prefix) {
    this(Bytes.UTF8(prefix));
  }

  /**
   * Constructor.
   * @throws IllegalArgumentException if the prefix is an empty byte array.
   */
  public ColumnPrefixFilter(final byte[] prefix) {
    if (prefix.length == 0) {
      throw new IllegalArgumentException("Empty prefix");
    }
    this.prefix = prefix;
  }

  @Override
  byte[] serialize() {
    return FilterPB.ColumnPrefixFilter.newBuilder()
      .setPrefix(Bytes.wrap(prefix))
      .build()
      .toByteArray();
  }

  @Override
  byte[] name() {
    return NAME;
  }

  @Override
  int predictSerializedSize() {
    return 1 + NAME.length + 3 + prefix.length;
  }

  @Override
  void serializeOld(final ChannelBuffer buf) {
    buf.writeByte((byte) NAME.length);     // 1
    buf.writeBytes(NAME);                  // 49
    HBaseRpc.writeByteArray(buf, prefix);  // 3 + prefix.length
  }

  public String toString() {
    return "ColumnPrefixFilter(" + Bytes.pretty(prefix) + ")";
  }

}