Constructor Detail

• NonLazyKeyValueScanner

  public NonLazyKeyValueScanner()

Method Detail

• requestSeek

  public boolean requestSeek(Cell kv,
                    boolean forward,
                    boolean useBloom)
                      throws IOException

  Description copied from interface: KeyValueScanner
  Similar to KeyValueScanner.seek(org.apache.hadoop.hbase.Cell) (or KeyValueScanner.reseek(org.apache.hadoop.hbase.Cell) if forward is true) but only does a seek operation after checking that it is really necessary for the row/column combination specified by the kv parameter. This function was added to avoid unnecessary disk seeks by checking row-column Bloom filters before a seek on multi-column get/scan queries, and to optimize by looking up more recent files first.

  Specified by:

  requestSeek in interface KeyValueScanner

  forward - do a forward-only "reseek" instead of a random-access seek

  useBloom - whether to enable multi-column Bloom filter optimization

  Throws:

  IOException

• realSeekDone

  public boolean realSeekDone()

  Description copied from interface: KeyValueScanner
  We optimize our store scanners by checking the most recent store file first, so we sometimes pretend we have done a seek but delay it until the store scanner bubbles up to the top of the key-value heap. This method is then used to ensure the top store file scanner has done a seek operation.

  Specified by:

  realSeekDone in interface KeyValueScanner

• enforceSeek

  public void enforceSeek()
                   throws IOException

  Description copied from interface: KeyValueScanner
  Does the real seek operation in case it was skipped by seekToRowCol(KeyValue, boolean) (TODO: Whats this?). Note that this function should be never called on scanners that always do real seek operations (i.e. most of the scanners). The easiest way to achieve this is to call KeyValueScanner.realSeekDone() first.

  Specified by:

  enforceSeek in interface KeyValueScanner

  Throws:

  IOException

• doRealSeek

  public static boolean doRealSeek(KeyValueScanner scanner,
                   Cell kv,
                   boolean forward)
                            throws IOException

  Throws:

  IOException

• shouldUseScanner

  public boolean shouldUseScanner(Scan scan,
                         Store store,
                         long oldestUnexpiredTS)

  Description copied from interface: KeyValueScanner
  Allows to filter out scanners (both StoreFile and memstore) that we don't want to use based on criteria such as Bloom filters and timestamp ranges.

  Specified by:

  shouldUseScanner in interface KeyValueScanner

  Parameters:

  scan - the scan that we are selecting scanners for

  store - the store we are performing the scan on.

  oldestUnexpiredTS - the oldest timestamp we are interested in for this query, based on TTL

  Returns:

  true if the scanner should be included in the query

• isFileScanner

  public boolean isFileScanner()

  Specified by:

  isFileScanner in interface KeyValueScanner

  Returns:

  true if this is a file scanner. Otherwise a memory scanner is assumed.

• getNextIndexedKey

  public Cell getNextIndexedKey()

  Specified by:

  getNextIndexedKey in interface KeyValueScanner

  Returns:

  the next key in the index (the key to seek to the next block) if known, or null otherwise