public void testRemoveHalfRecords() throws IOException {
    final int records = 10000;
    long seed = System.currentTimeMillis();
    MersenneTwisterFast mersenneTwisterFast = new MersenneTwisterFast(seed);

    System.out.println("testRemoveHalfRecords seed : " + seed);

    Map<OClusterPosition, byte[]> positionRecordMap = new HashMap<OClusterPosition, byte[]>();

    ORecordVersion recordVersion = OVersionFactory.instance().createVersion();
    recordVersion.increment();
    recordVersion.increment();

    for (int i = 0; i < records; i++) {
      int recordSize = mersenneTwisterFast.nextInt(3 * OClusterPage.MAX_RECORD_SIZE) + 1;

      byte[] bigRecord = new byte[recordSize];
      mersenneTwisterFast.nextBytes(bigRecord);

      final OPhysicalPosition physicalPosition = paginatedCluster.createRecord(bigRecord, recordVersion, (byte) 2);

      positionRecordMap.put(physicalPosition.clusterPosition, bigRecord);
    }

    int deletedRecords = 0;
    Assert.assertEquals(records, paginatedCluster.getEntries());
    Set<OClusterPosition> deletedPositions = new HashSet<OClusterPosition>();
    Iterator<OClusterPosition> positionIterator = positionRecordMap.keySet().iterator();
    while (positionIterator.hasNext()) {
      OClusterPosition clusterPosition = positionIterator.next();
      if (mersenneTwisterFast.nextBoolean()) {
        deletedPositions.add(clusterPosition);
        Assert.assertTrue(paginatedCluster.deleteRecord(clusterPosition));
        deletedRecords++;

        Assert.assertEquals(records - deletedRecords, paginatedCluster.getEntries());

        positionIterator.remove();
      }
    }

    Assert.assertEquals(paginatedCluster.getEntries(), records - deletedRecords);
    for (OClusterPosition deletedPosition : deletedPositions) {
      Assert.assertNull(paginatedCluster.readRecord(deletedPosition));
      Assert.assertFalse(paginatedCluster.deleteRecord(deletedPosition));
    }

    for (Map.Entry<OClusterPosition, byte[]> entry : positionRecordMap.entrySet()) {
      ORawBuffer rawBuffer = paginatedCluster.readRecord(entry.getKey());
      Assert.assertNotNull(rawBuffer);

      Assert.assertEquals(rawBuffer.version, recordVersion);
      Assert.assertEquals(rawBuffer.buffer, entry.getValue());
      Assert.assertEquals(rawBuffer.recordType, 2);
    }
  }
  public void testRemoveHalfRecordsAndAddAnotherHalfAgain() throws IOException {
    final int records = 10000;
    long seed = System.currentTimeMillis();
    MersenneTwisterFast mersenneTwisterFast = new MersenneTwisterFast(seed);

    System.out.println("testRemoveHalfRecordsAndAddAnotherHalfAgain seed : " + seed);

    Map<OClusterPosition, byte[]> positionRecordMap = new HashMap<OClusterPosition, byte[]>();

    ORecordVersion recordVersion = OVersionFactory.instance().createVersion();
    recordVersion.increment();
    recordVersion.increment();

    for (int i = 0; i < records; i++) {
      int recordSize = mersenneTwisterFast.nextInt(3 * OClusterPage.MAX_RECORD_SIZE) + 1;

      byte[] bigRecord = new byte[recordSize];
      mersenneTwisterFast.nextBytes(bigRecord);

      final OPhysicalPosition physicalPosition = paginatedCluster.createRecord(bigRecord, recordVersion, (byte) 2);

      positionRecordMap.put(physicalPosition.clusterPosition, bigRecord);
    }

    int deletedRecords = 0;
    Assert.assertEquals(records, paginatedCluster.getEntries());

    Iterator<OClusterPosition> positionIterator = positionRecordMap.keySet().iterator();
    while (positionIterator.hasNext()) {
      OClusterPosition clusterPosition = positionIterator.next();
      if (mersenneTwisterFast.nextBoolean()) {
        Assert.assertTrue(paginatedCluster.deleteRecord(clusterPosition));
        deletedRecords++;

        Assert.assertEquals(paginatedCluster.getEntries(), records - deletedRecords);

        positionIterator.remove();
      }
    }

    Assert.assertEquals(paginatedCluster.getEntries(), records - deletedRecords);

    for (int i = 0; i < records / 2; i++) {
      int recordSize = mersenneTwisterFast.nextInt(3 * OClusterPage.MAX_RECORD_SIZE) + 1;

      byte[] bigRecord = new byte[recordSize];
      mersenneTwisterFast.nextBytes(bigRecord);

      final OPhysicalPosition physicalPosition = paginatedCluster.createRecord(bigRecord, recordVersion, (byte) 2);

      positionRecordMap.put(physicalPosition.clusterPosition, bigRecord);
    }

    Assert.assertEquals(paginatedCluster.getEntries(), (long) (1.5 * records - deletedRecords));
  }
  public void testBackwardIteration() throws IOException {
    final int records = 10000;

    long seed = System.currentTimeMillis();
    MersenneTwisterFast mersenneTwisterFast = new MersenneTwisterFast(1381162033616L);
    System.out.println("testBackwardIteration seed : " + seed);

    NavigableMap<OClusterPosition, byte[]> positionRecordMap = new TreeMap<OClusterPosition, byte[]>();

    ORecordVersion recordVersion = OVersionFactory.instance().createVersion();
    recordVersion.increment();
    recordVersion.increment();

    for (int i = 0; i < records; i++) {
      int recordSize = mersenneTwisterFast.nextInt(2 * OClusterPage.MAX_RECORD_SIZE) + 1;
      byte[] record = new byte[recordSize];
      mersenneTwisterFast.nextBytes(record);

      final OPhysicalPosition physicalPosition = paginatedCluster.createRecord(record, recordVersion, (byte) 2);
      positionRecordMap.put(physicalPosition.clusterPosition, record);
    }

    Iterator<OClusterPosition> positionIterator = positionRecordMap.keySet().iterator();
    while (positionIterator.hasNext()) {
      OClusterPosition clusterPosition = positionIterator.next();
      if (mersenneTwisterFast.nextBoolean()) {
        Assert.assertTrue(paginatedCluster.deleteRecord(clusterPosition));
        positionIterator.remove();
      }
    }

    OPhysicalPosition physicalPosition = new OPhysicalPosition();
    physicalPosition.clusterPosition = OClusterPositionFactory.INSTANCE.valueOf(Long.MAX_VALUE);

    OPhysicalPosition[] positions = paginatedCluster.floorPositions(physicalPosition);
    Assert.assertTrue(positions.length > 0);

    positionIterator = positionRecordMap.descendingKeySet().iterator();
    int counter = 0;
    while (positionIterator.hasNext()) {
      Assert.assertTrue(positions.length > 0);

      OClusterPosition testedPosition = positionIterator.next();
      Assert.assertEquals(positions[positions.length - 1].clusterPosition, testedPosition);

      OPhysicalPosition positionToFind = positions[positions.length - 1];
      positions = paginatedCluster.lowerPositions(positionToFind);

      counter++;
    }

    Assert.assertEquals(paginatedCluster.getEntries(), counter);

    Assert.assertEquals(paginatedCluster.getFirstPosition(), positionRecordMap.firstKey());
    Assert.assertEquals(paginatedCluster.getLastPosition(), positionRecordMap.lastKey());
  }