Cypher syntax clarification. Multiple MATCH clauses vs using a comma [duplicate] - neo4j

Question

are these two Chypher statements identical:
//first
match (a)-[r]->(b),b-[r2]->c
//second
match (a)-[r]->(b)
match b-[r2]->c

Answer 1

The 2 Cypher statements are NOT identical. We can show this by using the PROFILE command, which shows you how the Cypher engine would perform a query.
In the following examples, the queries all end with RETURN a, c, since you cannot have a bare MATCH clause.
As you can see, the first query has a NOT(r == r2) filter that the second query does not. This is because Cypher makes sure that the result of a single MATCH clause does not contain duplicate relationships.
First query
profile match (a)-[r]->(b),b-[r2]->c return a,c;
==> +-----------------------------------------------+
==> | a | c |
==> +-----------------------------------------------+
==> | Node[1]{name:"World"} | Node[0]{name:"World"} |
==> +-----------------------------------------------+
==> 1 row
==> 2 ms
==>
==> Compiler CYPHER 2.3
==>
==> Planner COST
==>
==> Runtime INTERPRETED
==>
==> Projection
==> |
==> +Filter
==> |
==> +Expand(All)(0)
==> |
==> +Expand(All)(1)
==> |
==> +AllNodesScan
==>
==> +----------------+---------------+------+--------+----------------+----------------+
==> | Operator | EstimatedRows | Rows | DbHits | Identifiers | Other |
==> +----------------+---------------+------+--------+----------------+----------------+
==> | Projection | 1 | 1 | 0 | a, b, c, r, r2 | a; c |
==> | Filter | 1 | 1 | 0 | a, b, c, r, r2 | NOT(r == r2) |
==> | Expand(All)(0) | 1 | 2 | 4 | a, b, c, r, r2 | (b)-[r2:]->(c) |
==> | Expand(All)(1) | 2 | 2 | 8 | a, b, r | (b)<-[r:]-(a) |
==> | AllNodesScan | 6 | 6 | 7 | b | |
==> +----------------+---------------+------+--------+----------------+----------------+
==>
Second query
profile match (a)-[r]->(b) match b-[r2]->c return a,c;
==> +-----------------------------------------------+
==> | a | c |
==> +-----------------------------------------------+
==> | Node[1]{name:"World"} | Node[1]{name:"World"} |
==> | Node[1]{name:"World"} | Node[0]{name:"World"} |
==> +-----------------------------------------------+
==> 2 rows
==> 2 ms
==>
==> Compiler CYPHER 2.3
==>
==> Planner COST
==>
==> Runtime INTERPRETED
==>
==> Projection
==> |
==> +Expand(All)(0)
==> |
==> +Expand(All)(1)
==> |
==> +AllNodesScan
==>
==> +----------------+---------------+------+--------+----------------+----------------+
==> | Operator | EstimatedRows | Rows | DbHits | Identifiers | Other |
==> +----------------+---------------+------+--------+----------------+----------------+
==> | Projection | 1 | 2 | 0 | a, b, c, r, r2 | a; c |
==> | Expand(All)(0) | 1 | 2 | 4 | a, b, c, r, r2 | (b)-[r2:]->(c) |
==> | Expand(All)(1) | 2 | 2 | 8 | a, b, r | (b)<-[r:]-(a) |
==> | AllNodesScan | 6 | 6 | 7 | b | |
==> +----------------+---------------+------+--------+----------------+----------------+