Constructor Detail

• FilterBase

  public FilterBase()

Method Detail

• reset

  public void reset()
             throws IOException

  Filters that are purely stateless and do nothing in their reset() methods can inherit this null/empty implementation. Reset the state of the filter between rows. Concrete implementers can signal a failure condition in their code by throwing an IOException.

  Specified by:

  reset in class Filter

  Throws:

  IOException - in case an I/O or an filter specific failure needs to be signaled.

• filterRowKey

  public boolean filterRowKey(byte[] buffer,
                     int offset,
                     int length)
                       throws IOException

  Filters that do not filter by row key can inherit this implementation that never filters anything. (ie: returns false). Filters a row based on the row key. If this returns true, the entire row will be excluded. If false, each KeyValue in the row will be passed to Filter.filterKeyValue(Cell) below. Concrete implementers can signal a failure condition in their code by throwing an IOException.

  Specified by:

  filterRowKey in class Filter

  Parameters:

  buffer - buffer containing row key

  offset - offset into buffer where row key starts

  length - length of the row key

  Returns:

  true, remove entire row, false, include the row (maybe).

  Throws:

  IOException - in case an I/O or an filter specific failure needs to be signaled.

• filterAllRemaining

  public boolean filterAllRemaining()
                             throws IOException

  Filters that never filter all remaining can inherit this implementation that never stops the filter early. If this returns true, the scan will terminate. Concrete implementers can signal a failure condition in their code by throwing an IOException.

  Specified by:

  filterAllRemaining in class Filter

  Returns:

  true to end scan, false to continue.

  Throws:

  IOException - in case an I/O or an filter specific failure needs to be signaled.

• transformCell

  public Cell transformCell(Cell v)
                     throws IOException

  By default no transformation takes place Give the filter a chance to transform the passed KeyValue. If the Cell is changed a new Cell object must be returned.

  Specified by:

  transformCell in class Filter

  Parameters:

  v - the KeyValue in question

  Returns:

  the changed KeyValue

  Throws:

  IOException - in case an I/O or an filter specific failure needs to be signaled.

  See Also:

  The transformed KeyValue is what is eventually returned to the client. Most filters will return the passed KeyValue unchanged., for an example of a transformation. Concrete implementers can signal a failure condition in their code by throwing an {@link IOException}.

• transform

  @Deprecated
  public KeyValue transform(KeyValue currentKV)
                     throws IOException

  Deprecated. 
  WARNING: please to not override this method. Instead override transformCell(Cell). This is for transition from 0.94 -> 0.96

  Specified by:

  transform in class Filter

  Throws:

  IOException

• filterRowCells

  public void filterRowCells(List<Cell> ignored)
                      throws IOException

  Filters that never filter by modifying the returned List of Cells can inherit this implementation that does nothing. Chance to alter the list of Cells to be submitted. Modifications to the list will carry on Concrete implementers can signal a failure condition in their code by throwing an IOException.

  Specified by:

  filterRowCells in class Filter

  Parameters:

  ignored - the list of Cells to be filtered

  Throws:

  IOException - in case an I/O or an filter specific failure needs to be signaled.

• hasFilterRow

  public boolean hasFilterRow()

  Fitlers that never filter by modifying the returned List of Cells can inherit this implementation that does nothing. Primarily used to check for conflicts with scans(such as scans that do not read a full row at a time).

  Specified by:

  hasFilterRow in class Filter

  Returns:

  True if this filter actively uses filterRowCells(List) or filterRow().

• filterRow

  public boolean filterRow()
                    throws IOException

  Filters that never filter by rows based on previously gathered state from Filter.filterKeyValue(Cell) can inherit this implementation that never filters a row. Last chance to veto row based on previous Filter.filterKeyValue(Cell) calls. The filter needs to retain state then return a particular value for this call if they wish to exclude a row if a certain column is missing (for example). Concrete implementers can signal a failure condition in their code by throwing an IOException.

  Specified by:

  filterRow in class Filter

  Returns:

  true to exclude row, false to include row.

  Throws:

  IOException - in case an I/O or an filter specific failure needs to be signaled.

• getNextKeyHint

  @Deprecated
  public KeyValue getNextKeyHint(KeyValue currentKV)
                          throws IOException

  Deprecated. 
  This method is deprecated and you should override Cell getNextKeyHint(Cell) instead.

  Specified by:

  getNextKeyHint in class Filter

  Returns:

  KeyValue which must be next seeked. return null if the filter is not sure which key to seek to next.

  Throws:

  IOException - Function is Deprecated. Use Filter.getNextCellHint(Cell) instead.

• getNextCellHint

  public Cell getNextCellHint(Cell currentKV)
                       throws IOException

  Filters that are not sure which key must be next seeked to, can inherit this implementation that, by default, returns a null Cell. If the filter returns the match code SEEK_NEXT_USING_HINT, then it should also tell which is the next key it must seek to. After receiving the match code SEEK_NEXT_USING_HINT, the QueryMatcher would call this function to find out which key it must next seek to. Concrete implementers can signal a failure condition in their code by throwing an IOException.

  Specified by:

  getNextCellHint in class Filter

  Returns:

  KeyValue which must be next seeked. return null if the filter is not sure which key to seek to next.

  Throws:

  IOException - in case an I/O or an filter specific failure needs to be signaled.

• isFamilyEssential

  public boolean isFamilyEssential(byte[] name)
                            throws IOException

  By default, we require all scan's column families to be present. Our subclasses may be more precise. Check that given column family is essential for filter to check row. Most filters always return true here. But some could have more sophisticated logic which could significantly reduce scanning process by not even touching columns until we are 100% sure that it's data is needed in result. Concrete implementers can signal a failure condition in their code by throwing an IOException.

  Specified by:

  isFamilyEssential in class Filter

  Throws:

  IOException - in case an I/O or an filter specific failure needs to be signaled.

• createFilterFromArguments

  public static Filter createFilterFromArguments(ArrayList<byte[]> filterArguments)

  Given the filter's arguments it constructs the filter

  Parameters:

  filterArguments - the filter's arguments

  Returns:

  constructed filter object

• toString

  public String toString()

  Return filter's info for debugging and logging purpose.

  Overrides:

  toString in class Object

• toByteArray

  public byte[] toByteArray()
                     throws IOException

  Return length 0 byte array for Filters that don't require special serialization

  Specified by:

  toByteArray in class Filter

  Returns:

  The filter serialized using pb

  Throws:

  IOException - in case an I/O or an filter specific failure needs to be signaled.