public void deallocatePage(int pageNumber) throws IOException {
  assertWriting();
  validatePageNumber(pageNumber);
  _invalidPageBytes.rewind();
  _channel.write(_invalidPageBytes,getPageOffset(pageNumber));
  _globalUsageMap.addPageNumber(pageNumber);
}

public void deallocatePage ( int pageNumber ) throws IOException { assertWriting ( ) ; validatePageNumber ( pageNumber ) ; _invalidPageBytes . rewind ( ) ; _channel . write ( _invalidPageBytes , getPageOffset ( pageNumber ) ) ; _globalUsageMap . addPageNumber ( pageNumber ) ; }
deallocate a previously used page in the database .
