How to use

SingleRowCursor

in

org.h2.index

/** {@inheritDoc} */
@Override public Cursor find(Session session, SearchRow first, SearchRow last) {
  if (first == null || last == null || !Objects.equals(id(first), id(last)))
    return new GridH2Cursor(rows.values().iterator());
  return new SingleRowCursor(rows.get(id(first)));
}

@Override
public Cursor find(Session session, SearchRow first, SearchRow last) {
  if (first == null || last == null) {
    // TODO hash index: should additionally check if values are the same
    throw DbException.throwInternalError(first + " " + last);
  }
  Value v = first.getValue(indexColumn);
  /*
   * Sometimes the incoming search is a similar, but not the same type
   * e.g. the search value is INT, but the index column is LONG. In which
   * case we need to convert, otherwise the ValueHashMap will not find the
   * result.
   */
  v = v.convertTo(tableData.getColumn(indexColumn).getType());
  Row result;
  Long pos = rows.get(v);
  if (pos == null) {
    result = null;
  } else {
    result = tableData.getRow(session, pos.intValue());
  }
  return new SingleRowCursor(result);
}

/** {@inheritDoc} */
@Override public Cursor findFirstOrLast(Session session, boolean b) {
  try {
    H2Tree tree = treeForRead(threadLocalSegment());
    GridH2QueryContext qctx = GridH2QueryContext.get();
    return new SingleRowCursor(b ? tree.findFirst(filter(qctx)): tree.findLast(filter(qctx)));
  }
  catch (IgniteCheckedException e) {
    throw DbException.convert(e);
  }
}

/** {@inheritDoc} */
@Override public Cursor find(Session ses, SearchRow lower, SearchRow upper) {
  assert lower == null || lower instanceof GridH2SearchRow : lower;
  assert upper == null || upper instanceof GridH2SearchRow : upper;
  try {
    int seg = threadLocalSegment();
    H2Tree tree = treeForRead(seg);
    if (!cctx.mvccEnabled() && indexType.isPrimaryKey() && lower != null && upper != null &&
      tree.compareRows((GridH2SearchRow)lower, (GridH2SearchRow)upper) == 0) {
      GridH2Row row = tree.findOne((GridH2SearchRow)lower, filter(GridH2QueryContext.get()), null);
      return (row == null) ? GridH2Cursor.EMPTY : new SingleRowCursor(row);
    }
    else {
      return new H2Cursor(tree.find((GridH2SearchRow)lower,
        (GridH2SearchRow)upper, filter(GridH2QueryContext.get()), null));
    }
  }
  catch (IgniteCheckedException e) {
    throw DbException.convert(e);
  }
}

/** {@inheritDoc} */
@Override public Cursor find(Session session, SearchRow first, SearchRow last) {
  if (first == null || last == null || !Objects.equals(id(first), id(last)))
    return new GridH2Cursor(rows.values().iterator());
  return new SingleRowCursor(rows.get(id(first)));
}

/** {@inheritDoc} */
@Override public Cursor findFirstOrLast(Session ses, boolean first) {
  Lock l = lock.readLock();
  l.lock();
  try {
    checkClosed();
    if (!first)
      throw DbException.throwInternalError("Spatial Index can only be fetch by ascending order");
    Iterator<GridH2Row> iter = rowIterator(treeMap.keySet().iterator());
    return new SingleRowCursor(iter.hasNext() ? iter.next() : null);
  }
  finally {
    l.unlock();
  }
}

/** {@inheritDoc} */
@Override public Cursor findFirstOrLast(Session ses, boolean first) {
  ConcurrentNavigableMap<GridSearchRowPointer, GridH2Row> tree = treeForRead();
  GridSearchRowPointer res = null;
  Iterator<GridH2Row> iter = filter(first ? tree.values().iterator() :
    tree.descendingMap().values().iterator());
  if (iter.hasNext()) {
    GridSearchRowPointer r = iter.next();
    if ((first && compare(r, res) < 0) || (!first && compare(r, res) > 0))
      res = r;
  }
  return new SingleRowCursor((Row)res);
}

@Override
public Cursor find(Session session, SearchRow first, SearchRow last) {
  if (first == null || last == null) {
    // TODO hash index: should additionally check if values are the same
    throw DbException.throwInternalError();
  }
  Value v = first.getValue(indexColumn);
  /*
   * Sometimes the incoming search is a similar, but not the same type
   * e.g. the search value is INT, but the index column is LONG. In which
   * case we need to convert, otherwise the ValueHashMap will not find the
   * result.
   */
  v = v.convertTo(tableData.getColumn(indexColumn).getType());
  Row result;
  Long pos = rows.get(v);
  if (pos == null) {
    result = null;
  } else {
    result = tableData.getRow(session, pos.intValue());
  }
  return new SingleRowCursor(result);
}

@Override
public Cursor find(Session session, SearchRow first, SearchRow last) {
  if (first == null || last == null) {
    // TODO hash index: should additionally check if values are the same
    throw DbException.throwInternalError();
  }
  Value v = first.getValue(indexColumn);
  /*
   * Sometimes the incoming search is a similar, but not the same type
   * e.g. the search value is INT, but the index column is LONG. In which
   * case we need to convert, otherwise the ValueHashMap will not find the
   * result.
   */
  v = v.convertTo(tableData.getColumn(indexColumn).getType());
  Row result;
  Long pos = rows.get(v);
  if (pos == null) {
    result = null;
  } else {
    result = tableData.getRow(session, pos.intValue());
  }
  return new SingleRowCursor(result);
}

/** {@inheritDoc} */
@Override public Cursor findFirstOrLast(Session session, boolean b) {
  try {
    H2Tree tree = treeForRead(threadLocalSegment());
    GridH2QueryContext qctx = GridH2QueryContext.get();
    return new SingleRowCursor(b ? tree.findFirst(filter(qctx)): tree.findLast(filter(qctx)));
  }
  catch (IgniteCheckedException e) {
    throw DbException.convert(e);
  }
}

/** {@inheritDoc} */
@Override public Cursor find(Session ses, SearchRow lower, SearchRow upper) {
  try {
    assert lower == null || lower instanceof GridH2SearchRow : lower;
    assert upper == null || upper instanceof GridH2SearchRow : upper;
    int seg = threadLocalSegment();
    H2Tree tree = treeForRead(seg);
    if (!cctx.mvccEnabled() && indexType.isPrimaryKey() && lower != null && upper != null &&
      tree.compareRows((GridH2SearchRow)lower, (GridH2SearchRow)upper) == 0) {
      GridH2Row row = tree.findOne((GridH2SearchRow)lower, filter(GridH2QueryContext.get()), null);
      return (row == null) ? GridH2Cursor.EMPTY : new SingleRowCursor(row);
    }
    else {
      return new H2Cursor(tree.find((GridH2SearchRow)lower,
        (GridH2SearchRow)upper, filter(GridH2QueryContext.get()), null));
    }
  }
  catch (IgniteCheckedException e) {
    throw DbException.convert(e);
  }
}