Incorrect warning - cartesian product

[pjljvandelaar]

Configuration

Neo4j

OS

Steps to reproduce

The following two queries are equivalent:

MATCH
	(C1) -[:CppContains]-> (P1),
	(C2) -[:CppContains]-> (P2),
	(P1) -[R:CppCalls]-> (P2)
WHERE
	C1 <> C2
RETURN
	P1, P2, Count(R) AS Relations
ORDER BY Relations DESC

and

MATCH
	(C1) -[:CppContains]-> (P1) -[R:CppCalls]-> (P2) <-[:CppContains]- (C2) 
WHERE
	C1 <> C2
RETURN
	P1, P2, Count(R) AS Relations
ORDER BY Relations DESC

Actual behavior

The query

MATCH
	(C1) -[:CppContains]-> (P1),
	(C2) -[:CppContains]-> (P2),
	(P1) -[R:CppCalls]-> (P2)
WHERE
	C1 <> C2
RETURN
	P1, P2, Count(R) AS Relations
ORDER BY Relations DESC

is shown by neo4j as follows

With the following warning text (that pops up on hoover over)

The query

MATCH
	(C1) -[:CppContains]-> (P1) -[R:CppCalls]-> (P2) <-[:CppContains]- (C2) 
WHERE
	C1 <> C2
RETURN
	P1, P2, Count(R) AS Relations
ORDER BY Relations DESC

is shown by neo4j as follows

Expected behavior

I would have expected that both queries are treated equally by neo4j.
In fact, I think the warning for the first query is wrong.

Questions

Can you confirm that

• the queries are indeed equivalent.
• if so, neo4j should treat them equally.
• if so, the first query is wrongly treated by neo4j.

Thanks in advance for your answers and bug fix!

[pjljvandelaar]

Note that the equivalent query

MATCH
	(C1) -[:CppContains]-> (P1),
	(P1) -[R:CppCalls]-> (P2),
        (C2) -[:CppContains]-> (P2)
WHERE
	C1 <> C2
RETURN
	P1, P2, Count(R) AS Relations
ORDER BY Relations DESC

is also shown without any warning:

[SachinVasant]

Thank you so much for raising this issue @pjljvandelaar
I have pushed a fix for this which should go out in an upcoming version release.

Thanks and regards,
Sachin