code: func (c *Chunk) AppendPartialRow(colIdx int, row Row) {
  	for i, rowCol := range row.c.columns {
  		chkCol := c.columns[colIdx+i]
  		chkCol.appendNullBitmap(!rowCol.isNull(row.idx))
  		if rowCol.isFixed() {
  			elemLen := len(rowCol.elemBuf)
  			offset := row.idx * elemLen
  			chkCol.data = append(chkCol.data, rowCol.data[offset:offset+elemLen]...)
  		} else {
  			start, end := rowCol.offsets[row.idx], rowCol.offsets[row.idx+1]
  			chkCol.data = append(chkCol.data, rowCol.data[start:end]...)
  			chkCol.offsets = append(chkCol.offsets, int32(len(chkCol.data)))
  		}
  		chkCol.length++
  	}
  }
docs: // AppendPartialRow appends a row to the chunk.