rubenada commented on PR #5370:
URL: https://github.com/apache/calcite/pull/5370#issuecomment-6610059624
@vldpyatkov thanks for pushing this forward!
Quick question: IIUC the usage of SEARCH on a diamond shape graph could lead
to "duplicated" results, e.g.:
Edges: 0→1, 0→2, 1→3, 2→3. Node 3 can be reached two ways.
```
WITH RECURSIVE edges(src, dst) AS (VALUES (0,1), (0,2), (1,3), (2,3)),
walk(node) AS (
VALUES (0)
UNION
SELECT e.dst FROM walk AS w JOIN edges AS e ON e.src = w.node)
SELECT node FROM walk
```
Without `SEARCH`: 0,1,2,3
With `SEARCH DEPTH`: (0, [0]), (1, [0,1]), (2, [0,2]), (3, [0,1,3]), (3,
[0,2,3])
On the second case, 3 is returned two times (because paths differ).
Analogously, on a graph: 0→1, 1→3, 0→3
Without `SEARCH`: 0,1,3
With `SEARCH BREADTH`: (0, ROW(0,0)), (1, ROW(1,1)), (3, ROW(1,3)), (3,
ROW(2,3)).
On the second case, 3 is returned two times (because depths differ).
If this is the case, could we have some tests showing these cases? Shall we
document somehow this phenomenon?
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