Neo4j Cypher 2.0: Pass in params for batch match - relationships - neo4j

This question is similar to this: create relationships between nodes in parallel and this Neo4j: Best way to batch relate nodes using Cypher?
I would like to parameterize a batch for creating relationships using a Cypher query and Neo4jClient (a c# client for Neo4j).
How would I write this out (specifically focusing on performance) - i.e. using only match and create statements and not Merge as merge ends up timing out for some reason?
I was thinking I could do something like this ( as stated in that second SO link)
MATCH (s:ContactPlayer {ContactPrefixTypeId:{cptid}})
MATCH (c:ContactPrefixType {ContactPrefixTypeId:{cptid}})
CREATE c-[:CONTACT_PLAYER]->s
with params:
{
"query":...,
"params": {
"cptid":id1
}
}
But this doesn't work, because it's trying to match the property as an Array.
I modified it to use WHERE x.Y IN {params} but this was extremely slow. The second recommendation was to try to use the transactional endpoint for Neo4j but I'm unsure how to do that with Neo4jClient.
This was the recommendation from the 2nd SO link above:
{
"statements":[
"statement":...,
"parameters": {
"cptid":id1
},
"statement":...,
"parameters": {
"cptid":id2
}
]
}
I did see this pull request but did not see that it had been implemented yet: https://github.com/Readify/Neo4jClient/pull/26
Without transaction support, is there another way to do this?

What's the performance when you use the query below?
USING PERIODIC COMMIT 1000
MATCH (s:ContactPlayer), (c:ContactPrefixType)
WHERE s.ContactPrefixTypeId = c.ContactPrefixTypeId
CREATE c-[:CONTACT_PLAYER]->s
If you want to try out the periodic commit statement, you'll have to use version 2.1.0-M1 for now. Otherwise, you can leave it out.

Related

how to create multiple relationships in a single cypher statement

I must create a set of relationships, all having the same source and type, like in the following sample:
create (_1)-[:`typ`]->(:`x` {`name`:"Mark"})
create (_1)-[:`typ`]->(:`y` {`name`:"Jane"})
create (_1)-[:`typ`]->(:`z` {`name`:"John"})
...
I'd like to have a shorten way to write those statements, like following attempt?
create (_1)-[:`typ`]->[(:`x` {`name`:"Mark"}),
(:`y` {`name`:"Jane"}),
(:`z` {`name`:"John"})]
Any idea?
Thank you in advance.
Paolo
You could do it in a performant and easy way by this pattern:
{batch: [
{from:"alice#example.com",to:"bob#example.com",properties:{since:2012}},
{from:"alice#example.com",to:"charlie#example.com",properties:{since:2016}}]}
UNWIND {batch} as row
MATCH (from:Label {row.from})
MATCH (to:Label {row.to})
CREATE/MERGE (from)-[rel:KNOWS]->(to)
(ON CREATE) SET rel += row.properties
Taken with thanks from 5 Tips & Tricks for Fast Batched Updates of Graph Structures with Neo4j and Cypher by #MichaelHunger.

How to set "resultDataContents" in Neo4jrb?

I want to visualise data from Neo4j with the frontend-library D3.js in an Rails application, using Neo4jrb. For example I could use the following query to get my graph data.
query = "MATCH path = (a)-[b]->(c) RETURN path"
result = Neo4j::Session.current.query(query)
But this query is not giving me the exact data I want.
According to the Neo4j data visualisation guide there is a possibility to set the parameter resultDataContents to "graph". (
Neo4j documentation for "resultDataContents")
This is exactly what I need for my application. Is there any possibility to set this parameter in Neo4jrb, or another idea how to achieve such a result?
Unfortunately not currently. The neo4j-core gem (which the neo4j gem uses) was build to abstract away the REST format. The "graph" format returns data in a different way.
You have a couple of options. You could make the JSON queries yourself or you could retrieve the nodes and relationships from the queries that you perform and then build your own nodes/relationships structure which is returned. This might be more future-proof anyway if you ever want to switch to Bolt.
A way that you might do this in your case:
query = "MATCH path = (a)-[b]->(c) RETURN nodes(path) AS nodes, rels(path) AS rels"
result = Neo4j::Session.current.query(query)
response = {nodes: [], rels: []}
result.each do |row|
response[:nodes].concat(row.nodes)
response[:rels].concat(row.rels)
end
response[:nodes].uniq!
response[:rels].uniq!

Cypher query with literal map syntax & dynamic keys

I'd like to make a cypher query that generates a specific json output. Part of this output includes an object with a dynamic amount of keys relative to the children of a parent node:
{
...
"parent_keystring" : {
child_node_one.name : child_node_one.foo
child_node_two.name : child_node_two.foo
child_node_three.name : child_node_three.foo
child_node_four.name : child_node_four.foo
child_node_five.name : child_node_five.foo
}
}
I've tried to create a cypher query but I do not believe I am close to achieving the desired output mentioned above:
MATCH (n)-[relone:SPECIFIC_RELATIONSHIP]->(child_node)
WHERE n.id='839930493049039430'
RETURN n.id AS id,
n.name AS name,
labels(n)[0] AS type,
{
COLLECT({
child.name : children.foo
}) AS rel_two_representation
} AS parent_keystring
I had planned for children.foo to be a count of how many occurrences of each particular relationship/child of the parent. Is there a way to make use of the reduce function? Where a report would generate based on analyzing the array proposed below? ie report would be a json object where each key is a distinct RELATIONSHIP and the property value would be the amount of times that relationship stems from the parent node?
Thank you greatly in advance for guidance you can offer.
I'm not sure that Cypher will let you use a variable to determine an object's key. Would using an Array work for you?
COLLECT([child.name, children.foo]) AS rel_two_representation
I think, Neo4j Server API output by itself should be considered as any database output (like MySQL). Even if it is possible to achieve, with default functionality, desired output - it is not natural way for database.
Probably you should look into creating your own server plugin. This allows you to implement any custom logic, with desired output.

py2neo return number of nodes and relationships created

I need to create a python function such that it adds nodes and relationship to a graph and returns the number of created nodes and relationships.
I have added the nodes and relationship using graph.cypher.execute().
arr_len = len(dic_st[story_id]['PER'])
for j in dic_st[story_id]['PER']:
graph.cypher.execute("MERGE (n:PER {name:{name}})",name = j[0].upper()) #creating the nodes of PER in the story
print j[0]
for j in range(0,arr_len):
for k in range(j+1,arr_len):
graph.cypher.execute("MATCH (p1:PER {name:{name1}}), (p2:PER {name:{name2}}) WHERE upper(p1.name)<>upper(p2.name) CREATE UNIQUE (p1)-[r:in_same_doc {st_id:{st_id}}]-(p2)", name1=dic_st[story_id]['PER'][j][0].upper(),name2=dic_st[story_id]['PER'][k][0].upper(),st_id=story_id) #linking the edges for PER nodes
What I need is to return the number of new nodes and relationships created.
What I get to know from the neo4j documentation is that there is something called "ON CREATE" and "ON MATCH" for MERGE in cypher, but thats not being very useful.
The browser interface for neo4j do actually shows the number of nodes and relationship updated. This is what I need to return, but I am not getting quite the way for it to access it.
Any help please.
In case you need the exact counts of properties either created or updated then you have use "Match" with "Create" or "Match" with "Set" and then count the size of results. Merge may not return which ones are updated and which ones are created.
When you post your query against the Cypher endpoint of the neo4j REST API without using py2neo, you can include the argument "includeStats": true in your post request to get the node/relationship statistics. See this question for an example.
As far as I can tell, py2neo currently does not support additional parameters for the Cypher query (even though it is using the same API endpoints under the hood).
In Python, you could do something like this (using the requests and json packages):
import requests
import json
payload = {
"statements": [{
"statement": "CREATE (t:Test) RETURN t",
"includeStats": True
}]
}
r = requests.post('http://your_server_host:7474/db/data/transaction/commit',
data=json.dumps(payload))
print(r.text)
The response will include statistics about the number of nodes created etc.
{
"stats":{
"contains_updates":true,
"nodes_created":1,
"nodes_deleted":0,
"properties_set":1,
"relationships_created":0,
"relationship_deleted":0,
"labels_added":1,
"labels_removed":0,
"indexes_added":0,
"indexes_removed":0,
"constraints_added":0,
"constraints_removed":0
}
}
After executing your query using x = session.run(...) you can use x.summary.counters to get the statistics noted in Martin Perusse's answer. See the documentation here.
In older versions the counters are available as a "private" field under x._summary.counters.

NEO4J execute severals statement

How it's possible to run a collection of query like this (came from a spreadsheet copy) directly in one cypher query? one by one it's ok, but need 100 copy/paste
*******************************
MATCH (c:`alpha`)
where c.name = "a-01"
SET c.CP_PRI=1, c.TO_PRI=1, c.TA_PRI=2
return c ;
MATCH (c:`beta`)
where c.name = "a-02"
SET c.CP_PRI=1, c.TO_PRI=1, c.TA_PRI=0
return c ;
and 100 other lines ...
*********************************
you may try the 'union' clause, which joins the results of queries into one big-honkin result set:
http://docs.neo4j.org/chunked/milestone/query-union.html
That said - the root behavior of what you are trying to do could use some details - maybe there's a better way to write the query - you could use Excel to 'build' the unified query via calculations / macros, you could possibly write a unified query that combines the rules you are trying to follow, there's a lot of options, but it's hard to know a starting direction w/o context....
Talking about the REST API you can use the transactional endpoint in Neo4J 2.0, or the batch endpoint in Neo4J 1.x.
If you want to use the shell, have a look to the import page, in particular the neo4j-shell-tools where they're importing massive quantity of data batching multiple queries.

Resources