Thes operators explore the graph by expanding graph patterns.
Expand All
Given a start node, expand-all will follow relationships coming in or out, depending on the pattern relationship. Can also handle variable length pattern relationships.
Query
MATCH (p:Person { name: "me" })-[:FRIENDS_WITH]->(fof)
RETURN fof
Query Plan
+-----------------+----------------+------+---------+--------------------+----------------------------+ | Operator | Estimated Rows | Rows | DB Hits | Variables | Other | +-----------------+----------------+------+---------+--------------------+----------------------------+ | +ProduceResults | 0 | 1 | 0 | fof | fof | | | +----------------+------+---------+--------------------+----------------------------+ | +Expand(All) | 0 | 1 | 2 | anon[30], fof -- p | (p)-[:FRIENDS_WITH]->(fof) | | | +----------------+------+---------+--------------------+----------------------------+ | +NodeIndexSeek | 1 | 1 | 2 | p | :Person(name) | +-----------------+----------------+------+---------+--------------------+----------------------------+ Total database accesses: 4
Expand Into
When both the start and end node have already been found, expand-into is used to find all connecting relationships between the two nodes.
Query
MATCH (p:Person { name: "me" })-[:FRIENDS_WITH]->(fof)-->(p)
RETURN fof
Query Plan
+-----------------+----------------+------+---------+------------------------------+----------------------------+ | Operator | Estimated Rows | Rows | DB Hits | Variables | Other | +-----------------+----------------+------+---------+------------------------------+----------------------------+ | +ProduceResults | 0 | 0 | 0 | fof | fof | | | +----------------+------+---------+------------------------------+----------------------------+ | +Filter | 0 | 0 | 0 | anon[30], anon[53], fof, p | NOT(anon[30] == anon[53]) | | | +----------------+------+---------+------------------------------+----------------------------+ | +Expand(Into) | 0 | 0 | 0 | anon[30] -- anon[53], fof, p | (p)-[:FRIENDS_WITH]->(fof) | | | +----------------+------+---------+------------------------------+----------------------------+ | +Expand(All) | 0 | 0 | 1 | anon[53], fof -- p | (p)<--(fof) | | | +----------------+------+---------+------------------------------+----------------------------+ | +NodeIndexSeek | 1 | 1 | 2 | p | :Person(name) | +-----------------+----------------+------+---------+------------------------------+----------------------------+ Total database accesses: 3
Optional Expand All
Optional expand traverses relationships from a given node, and makes sure that predicates are evaluated before producing rows.
If no matching relationships are found, a single row with NULL for the relationship and end node variable is produced.
Query
MATCH (p:Person) OPTIONAL MATCH (p)-[works_in:WORKS_IN]->(l) WHERE works_in.duration > 180 RETURN p, l
Query Plan
+----------------------+----------------+------+---------+------------------+------------------------------+ | Operator | Estimated Rows | Rows | DB Hits | Variables | Other | +----------------------+----------------+------+---------+------------------+------------------------------+ | +ProduceResults | 14 | 15 | 0 | l, p | p, l | | | +----------------+------+---------+------------------+------------------------------+ | +OptionalExpand(All) | 14 | 15 | 44 | l, works_in -- p | (p)-[works_in:WORKS_IN]->(l) | | | +----------------+------+---------+------------------+------------------------------+ | +NodeByLabelScan | 14 | 14 | 15 | p | :Person | +----------------------+----------------+------+---------+------------------+------------------------------+ Total database accesses: 59