+---+---+---+
| a | b | c |
+---+---+---+
| 1 | a+| a+|
|   | b | b+|
|   |   | c |
| 3 | a+| a+|
|   | b | b+|
|   |   | c |
| 2 | a+| a+|
|   | b | b+|
|   |   | c |
+---+---+---+
(3 rows)

