The shortestPath: shortestPath( (ea)<-[:maps_to*]-(eb) )
before:
+VarLengthExpand(All) | 128 | 669618290 | 1494585385 | |
(ea)<-[:maps_to*]-(eb)
after:
| +ShortestPath | 28884702 | 678 | 169955 |
| +CartesianProduct | 28884702 | 169955 | 0 |
Since I have a lot of duplicate paths I assume the shortest path only
traverses a path once giving me a distinct path. Before I would traverse
all different path combinations (some of them multiple times) and then
filter them out with a distinct.
I think I misunderstood what the shortest path algorithm does.
On Tuesday, 17 January 2017 14:47:55 UTC+1, Michael Hunger wrote:
>
> Which one did the change and would you be able to share the query plan for
> that fast query with us?
>
> Michael
>
> On Tue, Jan 17, 2017 at 10:46 AM, <tomasz....@closeit.cz <javascript:>>
> wrote:
>
>> Did the change and the time went down to 20 seconds!
>>
>> Incredible.
>>
>> Thanks for the hint!
>>
>>
>> On Tuesday, 17 January 2017 07:59:52 UTC+1, tomasz....@closeit.cz wrote:
>>>
>>> Yes, there are indexes.
>>>
>>> I was wondering about the shortest path but I need all the paths that
>>> end at specific nodes, usually they will not be the shortests. I will try
>>> to see if the results are the same with this modification.
>>>
>>> On Tuesday, 17 January 2017 03:31:59 UTC+1, Michael Hunger wrote:
>>>>
>>>> I presume you have an index / constraint on nodeType1.fullname AND
>>>> nodeType1.name?!
>>>>
>>>> not sure why you do the pattern match first and only then the property
>>>> lookup.
>>>>
>>>> What version are you using? in Neo4j 3.1 for the query below you should
>>>> see much better performance:
>>>>
>>>> match (ea:nodeType1 {name:"something1"})<-[:maps_to*]-(eb:nodeType1)
>>>> where eb.fullname starts with "something"
>>>> with distinct ea, eb
>>>> return ea.name <http://el.name/>, eb.name <http://et.name/>;
>>>>
>>>> I would also think that shortest-path is much more sensible here:
>>>>
>>>> match (ea:nodeType1 {name:"something1"})
>>>> match (eb:nodeType1) where eb.fullname starts with "something"
>>>> match shortestPath( (ea)<-[:maps_to*]-(eb) )
>>>> with distinct ea, eb
>>>> return ea.name <http://el.name/>, eb.name <http://et.name/>;
>>>>
>>>> On Mon, Jan 16, 2017 at 9:19 PM, <tomasz....@closeit.cz> wrote:
>>>>
>>>>> Hi, I have a very expensive query that I'm trying to figure out how to
>>>>> optimise.
>>>>>
>>>>> match (ea:nodeType1 {name:"something1"})<-[:maps_to*]-(eb:nodeType1)
>>>>> with distinct ea, eb match (eb) where eb.fullname starts with
>>>>> "something" return ea.name <http://el.name/>, eb.name
>>>>> <http://et.name/>;
>>>>>
>>>>> I've used the profiler and as expected the expand all is the most
>>>>> expensive part of the operation
>>>>>
>>>>> +Filter | 128 | 334812480 | 669618290 |
>>>>> |
>>>>> +VarLengthExpand(All) | 128 | 669618290 | 1494585385 | |
>>>>> (ea)<-[:maps_to*]-(eb)
>>>>>
>>>>>
>>>>>
>>>>> I've used the profiler and brought down the running time from 3 hours
>>>>> to 2,15. I then tried the enterprise version hoping that the query would
>>>>> use the available processors but it used only one so I'm assuming that
>>>>> cypher is not parallelizable.
>>>>>
>>>>> Is there some quick win to speed up a distinct path query or do I have
>>>>> to write my own using the java api?
>>>>>
>>>>> p.s: the query might not compile as I've tried to summarise the gist
>>>>> of the issue.
>>>>>
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>>>>
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