I have a database containing millions of nodes and edge data and I want to get all the nodes and relationships data between two specified nodes.
Below is the sample data for the graph which has 7 nodes and 7 relationships.
To traverse from 1st node to 7th node I can use the variable length relationship approach and can get the nodes and relationships in between the first and 7th nodes (but in this approach we need to know the number of relationships and nodes between 1st and 7th node).
For using variable length relationship approach we have to specify the number where we will get the end node and it traverses in one direction.
But in my case I know the start and end node and don't know how many relationships and nodes are in between them. Please suggest how I can write a Cypher query for this case.
I have used the APOC spanning tree procedure where it returns ‘path’ from the 1st and 7th element, but it does not return the nodes and relationships. Can I get nodes and relationships data in return using the spanning tree procedure and how?
Is there any other way to get all nodes and relations between two nodes without using the APOC procedure?
Here is query with apoc procedure:
MATCH (start:temp {Name:"Joel"}), (end:temp {Name:"Jack"}) CALL apoc.path.spanningTree(start,{terminatorNodes:[end]}) YIELD path return path
Note: In our graph database nodes can have multi direction relations.
[Sample nodes and relationships snapshot]
: https://i.stack.imgur.com/nN9hk.png
I assume you do not want to have duplicates in your result, so my approach would be this
MATCH (start:temp {Name:"Joel"}), (end:temp {Name:"Jack"})
MATCH p=shortestPath((start)-[*]->(end))
UNWIND nodes(p) AS node
UNWIND relationships(p) AS rel
RETURN COLLECT(DISTINCT node) as nodes, COLLECT(DISTINCT rel) as rels
Might be better to use shortestPath operator to find the shortest path between two nodes.
MATCH (start:temp {Name:"Joel"}), (end:temp {Name:"Jack"})
MATCH p=shortestPath((start)-[*]->(end))
RETURN nodes(p) as nodes, relationships(p) as rels
Related
If I do the query
MATCH (:Label1 {prop1: "start node"}) -[relationships*1..10]-> ()
UNWIND relationships as relationship
RETURN DISTINCT relationship
How do I get nodes for each of acquired relationship to get result in format:
╒════════╤════════╤═══════╕
│"from" │"type" │"to" │
╞════════╪════════╪═══════╡
├────────┼────────┼───────┤
└────────┴────────┴───────┘
Is there a function such as type(r) but for getting nodes from relationship?
RomanMitasov and ray have working answers above.
I don't think they quite get at what you want to do though, because you're basically returning every relationship in the graph in a sort of inefficient way. I say that because without a start or end position, specifying a path length of 1-10 doesn't do anything.
For example:
CREATE (r1:Temp)-[:TEMP_REL]->(r2:Temp)-[:TEMP_REL]->(r3:Temp)
Now we have a graph with 3 Temp nodes with 2 relationships: from r1 to r2, from r2 to r3.
Run your query on these nodes:
MATCH (:Temp)-[rels*1..10]->(:Temp)
UNWIND rels as rel
RETURN startNode(rel), type(rel), endNode(rel)
And you'll see you get four rows. Which is not what you want because there are only two distinct relationships.
You could modify that to return only distinct values, but you're still over-searching the graph.
To get an idea of what relationships are in the graph and what they connect, I use a query like:
MMATCH (n)-[r]->(m)
RETURN labels(n), type(r), labels(m), count(r)
The downside of that, of course, is that it can take a while to run if you have a very large graph.
If you just want to see the structure of your graph:
CALL db.schema.visualization()
Best wishes and happy graphing! :)
Yes, such functions do exist!
startNode(r) to get the start node from relationship r
endNode(r) to get the end node
Here's the final query:
MATCH () -[relationships*1..10]-> ()
UNWIND relationships as r
RETURN startNode(r) as from, type(r) as type, endNode(r) as to
My graph is a directed acyclical graph. I would like to query for the subgraph of a given parent node, but then filter out subgraphs that have a relationship to another parent node. I created an image to illustrate.
For example I would like to select the subgraph (C)-[r]->(D), but exclude (B)-[r]->(E) because it is a child of (A).
I have written the following Cypher query, which includes a call to apoc.path.subpgrahAll(), it filters out (B), but it doesn't filter out nodes like (E)
MATCH (n {id: 'C'})
CALL apoc.path.subgraphAll(n, {relationshipFilter: 'CONNECTED>'})
YIELD nodes, relationships
UNWIND nodes as node
WITH node
WHERE SIZE(()-[:CONNECTED]->(node)) = 1
RETURN node
This may work for you:
CALL apoc.path.subgraphAll(n, {relationshipFilter: 'CONNECTED>'}) YIELD nodes, relationships
UNWIND nodes as node
WITH node
WHERE SIZE((node)<-[:CONNECTED]-()) = 1
RETURN node
By the way, in Cypher patterns, you need to precede a relationship type with a colon, which was one of the problems (but not the main one) with your query.
I have different nodes that share one same property field, i need to merge these nodes into one and in the same time copy all the rest of the other properties in the merge node.
example:
(n1,g,p1) (n2,g,p2) (n3,g,p3) =>(n,g,p1,p2,p3)
Important to Note that i don't need the apoc solutions since user defined functions dosen't work in CAPS that i m working at
update :
geohash is the field that have a repeated values, so i want to merge the nodes by this field .
The CAPS team gave me this cypher query to have distinct geohash nodes from the intial graph:
CATALOG CREATE GRAPH temp {
FROM GRAPH session.inputGraph
MATCH (n)
WITH DISTINCT n.geohash AS geohash
CONSTRUCT
CREATE (:HashNode {geohash: geohash})
RETURN GRAPH
}
, however it still missing is the collect of the rest of the properties on the merged nodes.
I haven't a problem for the relationship ,cause we can copy them later from the intial graph:
FROM GRAPH inputGraph
MATCH (from)-[via]->(to)
FROM GRAPH temp
MATCH (n), (m)
WHERE from.geohash = n. AND AND to.geohash = m.geohash
CONSTRUCT
CREATE (n)-[COPY OF via]->(m)
RETURN GRAPH
It's not 100% possible in pure cypher, that's why there is an APOC procedure for that.
To merge two nodes , you have to :
create the merge node with all the properties
to create all the relationship of the nodes on the merge one
For the first part it's possible in cypher. Example :
MATCH (n) WHERE id(n) IN [106, 68]
WITH collect(n) AS nodes
CREATE (new:MyNode)
with nodes, new
UNWIND nodes as node
SET new += properties(node)
RETURN new
But for the second part, you need to be able to create relationship with a dynamic type and dynamic direction, and this is not allowed in cypher ...
In a graph where the following nodes
A,B,C,D
have a relationship with each nodes successor
(A->B)
and
(B->C)
etc.
How do i make a query that starts with A and gives me all nodes (and relationships) from that and outwards.
I do not know the end node (C).
All i know is to start from A, and traverse the whole connected graph (with conditions on relationship and node type)
I think, you need to use this pattern:
(n)-[*]->(m) - variable length path of any number of relationships from n to m. (see Refcard)
A sample query would be:
MATCH path = (a:A)-[*]->()
RETURN path
Have also a look at the path functions in the refcard to expand your cypher query (I don't know what exact conditions you'll need to apply).
To get all the nodes / relationships starting at a node:
MATCH (a:A {id: "id"})-[r*]-(b)
RETURN a, r, b
This will return all the graphs originating with node A / Label A where id = "id".
One caveat - if this graph is large the query will take a long time to run.
I'm struggling with a problem despite having read a lot of documentation... I'm trying to find my graph root node (or nodes, they may be several top nodes) and counting their immediate children (all relations are typed :BELONGS_TO)
My graph looks like this (cf. attached screenshot). I have been trying the following query which works as long as the root node only has ONE incomming relationship, and it doesn not when it has more than one. (i'm not realy familiar with the cyhper language yet).
MATCH (n:Somelabel) WHERE NOT (()-[:BELONGS_TO]->(n:Somelabel)) RETURN n
Any help would be much appreciated ! (i haven't even tried to count the root nodes immediate children yet...which would be "2" according to my graph)
Correct query was given by cybersam
MATCH (n:Somelabel) WHERE NOT (n)-[:BELONGS_TO]->() RETURN n;
MATCH (n:Somelabel)<-[:BELONGS_TO]-(c:Somelabel)
WHERE NOT (n)-[:BELONGS_TO]->() RETURN n, count(c);
Based on your diagram, it looks like you are actually looking for "leaf" nodes. This query will search for all Somelabel nodes that have no outgoing relationships, and return each such node along with a count of the number of distinct nodes that have a relationship pointing to that node.
MATCH (n:Somelabel)
WHERE NOT (n)-[:BELONGS_TO]->()
OPTIONAL MATCH (m)-[:BELONGS_TO]->(n)
RETURN n, COUNT(DISTINCT m);
If you are actually looking for all "root" nodes, your original query would have worked.
As a sanity check, if you have a specific node that you believe is a "leaf" node (let's say it has an id value of 123), this query should return a single row with null values for r and m. If you get non-null results, then you actually have outgoing relationships.
MATCH (n {id:123})
OPTIONAL MATCH (n)-[r]->(m)
RETURN r, m