Thanks, Michael. I also created the index on value :)
For shortestPath, seems I have to specify the max depth, otherwise, it
won't work. *Presume that I don't know the max depth, how should this
work?*
MATCH p=shortestPath((e:Event { value:123 })-[:NEXT*]->(e2:Event {
value:200 }))
RETURN length(p)
or
MATCH p=shortestPath((e:Event { value:123 })-[*]->(e2:Event { value:200 }))
RETURN length(p)
btw, without shortest path, it will easily go into infinite loop...
match p=(e:Event {value:123})-[:NEXT*0..2000]->(d2:Event {value:200})
return length(p)
Thanks,
Gris
On Friday, December 5, 2014 9:15:31 AM UTC+13, Michael Hunger wrote:
>
> You shouldn't use neo4j console for tests like that. It is meant to be an
> in-memory sandbox for playing around or demoing small datasets (up to 200
> nodes).
> That's why it has a hard request limit to not affect other sandboxes
> running on the same system.
>
> I'd change your first query to this
>
> WITH range(1,1000) AS Ids unwind Ids AS id MERGE (e:Event { value:id })
> WITH COLLECT(e) AS events FOREACH (i IN range(0,length(events)-2)|
> FOREACH (e1 IN [events[i]]|
> foreach(e2 IN [events[i+1]]| CREATE UNIQUE (e1)-[:NEXT]->(e2))))
>
> Then create an index: create index on :Event(value)
>
> Match the nodes first and then compute the path:
>
> MATCH (e:Event { value:123 }),(e2:Event { value:125 })
> MATCH p=(e)-[:NEXT*0..150]->(e2)
> RETURN length(p)
>
> Even better use shortest-path for your query
>
> MATCH p=shortestPath((e:Event { value:123 })-[:NEXT*..150]->(e2:Event {
> value:200 }))
> RETURN length(p)
>
> Cheers, Michael
>
>
> On Thu, Dec 4, 2014 at 5:19 AM, grissimo <[email protected] <javascript:>>
> wrote:
>
>> Hi
>> I'm a newbie for neo4j, I've build up a linked list below:
>>
>> ------------------------------------
>> WITH range(1,10000) AS Ids unwind Ids AS id
>> MERGE (e1:Event { value:id })
>>
>>
>> MATCH (e:Event)
>> WITH COLLECT(e) as events
>> foreach (i in range(0,length(events)-2)|
>> foreach(e1 in [events[i]]|foreach (e2 in [events[i+1]]|
>> create unique (e1)-[:NEXT]->(e2))))
>> -------------------------
>>
>>
>> I tried with below query in http://console.neo4j.org/ but came up with
>> error as follow.
>> Error: org.neo4j.kernel.guard.GuardOperationsCountException: max ops (ops
>> =1000001)
>>
>> MATCH p=(e:Event { value:123 })-[:NEXT*0..150]->(e2:Event { value:125 })
>> RETURN length(p)
>>
>> Obviously, this is not a good way for doing this.
>>
>> What I really want is to get the path depth between two specific nodes
>> with NEXT relationship.
>>
>> MATCH p=(e:Event { value:123 })-*[:NEXT*]*->(e2:Event { value:125 })
>> RETURN length(p)
>>
>>
>> or assumed that I created a time tree(as here
>> <http://www.markhneedham.com/blog/2014/04/19/neo4j-cypher-creating-a-time-tree-down-to-the-day/>),
>>
>> and series of event with (event)-[:HAPPONED_ON->(d:Day), I want to
>> calculate how many days between these two days.
>>
>> Is there a correct/good way to calculate the path depth?
>>
>>
>> Regards
>>
>>
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