Cypher Query to to get having minimum 2 edges?

[apremgeorge]

Hi,
Q1: May I know cypher query to find the nodes having minimum 2 edges, either 2 In minimum, or 1 in and 1 out minimum?
based on Degree, I did that, i.e having deg > 2, but without running degree algorithm

Thanks

[stefan_armbrust · Accepted solution]

MATCH (n) WHERE size( (n)--() ) > 2 RETURN n

should do the trick.

[bhooyman]

That’s a full scan of the relationships file, correct? Even worse, most likely a full scan of the nodes file, plus a relationship pointer chase for each node.

[stefan_armbrust]

No. "Just" a full scan of nodes file. Getting the degree of a node is a O(n) operation for n<50 and a O(1) for n>=50.

[bhooyman]

That’s interesting. I thought I understood Neo4j internals and file record layout.

Can you educate me? Or tell me what part of the documentation I missed?

Thx

[dana_canzano]

Neo4j records a pre-calculated value for the following

Count of Nodes , i.e. match (n) return count(n);
Count of Nodes per label, i.e. match (n:Person) return count(n);
Count of relationship types per Node and direction, i.e. match (n) return size( (n)-[:FOLLOWS]->() );

if you PROFILE or EXPLAIN the above Cypher statements you should see a block referring to 'CountStore'

[bhooyman]

Super! Which version of Neo4j introduced this?

[dana_canzano]

introduced what?
the precalculated values at

Count of Nodes , i.e. match (n) return count(n);
Count of Nodes per label, i.e. match (n:Person) return count(n);
Count of relationship types per Node and direction, i.e. match (n) return size( (n)-[:FOLLOWS]->() );

has been in Neo4j since at least Neo4j version 2.3, if not earlier