Michael, awesome, thank you.
just to make sure I understand correctly, in this case, when you say 'cross
path comparison',
what are the 2 paths you are referring to?
On Tuesday, January 21, 2014 11:21:32 AM UTC-6, Michael Hunger wrote:
>
> Right, cross path comparisons are not yet used to shortcut path-finding
>
> so if you rewrite your query to this, it will actually filter down the
> paths eagerly
>
> MATCH (me:Member {id: 11700})
> WITH me, me.birth_year as birth_year
> MATCH
> (me)-[ra:preferred_store]->(s)<-[rb:preferred_store]-(other)-[rc:ordered]->()<-[rd:product]-(sv:StyleVariant)
> WHERE abs(other.birth_year - birth_year ) < {age_difference_range} AND
> sv.cached_available = 1
> ....
>
>
>
> Am 21.01.2014 um 18:19 schrieb Javad Karabi <[email protected]<javascript:>
> >:
>
> Michael, I apologize, I will send you a copy of the query + profile too.
> In my actual query, I am using a parameter of the cypher query:
> WHERE other.birth_year > (me.birth_year - {age_difference_range})
> AND other.birth_year < (me.birth_year + {age_difference_range})
>
> here is the relevant profile portion:
> Filter
> pred="(((Property(other,birth_year(66)) >
> Subtract(Property(me,birth_year(66)),Literal(10)) AND
> Property(other,birth_year(66)) <
> Add(Property(me,birth_year(66)),Literal(10))) AND
> Property(sv,cached_available(71)) == Literal(1)) AND
> hasLabel(sv:StyleVariant(13)))",
> _rows=47,
> _db_hits=4860
>
>
>
> On Tuesday, January 21, 2014 11:11:57 AM UTC-6, Michael Hunger wrote:
>>
>> The problem is cross-path expressions, which are not yet handled in that
>> manner
>>
>> for simple expressions that only contain a single piece of the path
>> (node, rel) and things that have been evaluated before (parameters,
>> literals, previous computations) WILL be used to shortcut the path
>> evaluation.
>>
>> but if you do: n1--n2--n3
>>
>> and then WHERE n2.foo > n1.bar it will be only applied AFTER the path
>>
>> if you do: WHERE n1.foo > 10 it will be applied DURING the path traversal
>>
>> HTH
>>
>> Michael
>>
>> Am 21.01.2014 um 18:08 schrieb Javad Karabi <[email protected]>:
>>
>> You will notice:
>> "WHERE (Property(NodeIdentifier(),cached_available(71)) == Literal(1)" in
>> the TraversalMatcher() portion, the very first function of the profile..
>>
>> I believe that this is what is meant when the documentation says that the
>> WHERE clause is not done after, (therefore during) the matching process.
>>
>> However, you will also notice that immediately following that function,
>> is Filter(), which is then filtering based on the ">" and "<" predicates of
>> the query.
>>
>> obviously, the best case scenario would be if the ">" and "<" tests
>> occurred inside TraversalMatcher(), i think
>>
>> On Tuesday, January 21, 2014 11:06:06 AM UTC-6, Javad Karabi wrote:
>>>
>>> Mark, I have emailed you the query and profile for both cases.
>>>
>>> On Tuesday, January 21, 2014 10:55:03 AM UTC-6, Javad Karabi wrote:
>>>>
>>>> Mark, I would be happy to. Give me a moment and I will post them.
>>>>
>>>> Michael,
>>>>
>>>> - Kernel version
>>>>
>>>> neo4j-browser, version: 2.0.0
>>>> -
>>>>
>>>>
>>>> On Tuesday, January 21, 2014 10:49:37 AM UTC-6, Michael Hunger wrote:
>>>>>
>>>>> Java, what version are you using?
>>>>>
>>>>> 2.0 final?
>>>>>
>>>>> Michael
>>>>>
>>>>> Am 21.01.2014 um 17:29 schrieb Javad Karabi <[email protected]>:
>>>>>
>>>>> from what I can tell, if there where clause is ">" or "<" (as it is in
>>>>> the actual query which i am using, not in this example query...) then the
>>>>> WHERE predicate _is in fact_ a filter, applied _after_ the match. It
>>>>> looks
>>>>> to me that "TraversalMatcher()" does not apply predicates which involve >
>>>>> or <, but instead delegates this to "Filter()" after the fact, which does
>>>>> not correlate with what is stated on the documentation.
>>>>>
>>>>> On Tuesday, January 21, 2014 10:25:41 AM UTC-6, Javad Karabi wrote:
>>>>>>
>>>>>> (c:Customer)-[:ordered]->(p:Product)-[:category]->(:Category)
>>>>>>
>>>>>> Now, say that there are 2:
>>>>>> c-[:ordered]->(:Product { name: "pants", quantity: 10})
>>>>>> c-[:ordered]->(:Product { name: "shirt", quantity: 5})
>>>>>>
>>>>>> Now, say that if I only want to cross the category relationship if
>>>>>> the p.quantity > 6
>>>>>>
>>>>>> In the most basic way, I would do:
>>>>>>
>>>>>> (c:Customer)-[:ordered]->(p:Product)-[:category]->(cat:Category)
>>>>>> WHERE p.quantity > 6
>>>>>>
>>>>>> However, I figured that maybe neo4j would (non-optimally) traverse
>>>>>> the entire path _then_ filter where on top of the path.
>>>>>>
>>>>>> So what I did was:
>>>>>>
>>>>>> MATCH (c:Customer)-[:ordered]->(p:Product)
>>>>>> WHERE p.quantity > 6
>>>>>> WITH p
>>>>>> MATCH p-[:category]->(cat:Category)
>>>>>>
>>>>>> This, I figured, would then allow neo4j to cross out to all the
>>>>>> product nodes, as I would need them anyway in order to filter out the
>>>>>> ones
>>>>>> which have a quantity of less than 6.
>>>>>>
>>>>>>
>>>>>> Now... finally to my question.
>>>>>> The following URL:
>>>>>> http://docs.neo4j.org/chunked/stable/query-match.html
>>>>>> states that:
>>>>>> WHERE defines the MATCH patterns in more detail. The predicates are
>>>>>> part of the pattern description, not a filter applied after the matching
>>>>>> is
>>>>>> done.
>>>>>>
>>>>>> So, my question is, if the predicates (specifically p.quantity > 6)
>>>>>> are part of the pattern description, and _not_ applied _after_ matching
>>>>>> (therefore applied before or during), then cutting the query with the
>>>>>> WITHs
>>>>>> would be a moot point
>>>>>>
>>>>>> So, I would think that
>>>>>>
>>>>>> (c:Customer)-[:ordered]->(p:Product)-[:category]->(cat:Category)
>>>>>> WHERE p.quantity > 6
>>>>>> would be sufficient, , as neo4j _would not_ actually traverse to
>>>>>> cat, since it would apply the filter during the match process.
>>>>>>
>>>>>> However, in practice, I notice that using WITH is actually faster. Is
>>>>>> there any possible reason for this?
>>>>>> It may be necessary for me to show my query exactly, I also have the
>>>>>> profile data for the query, which I am currently analyzing
>>>>>>
>>>>>
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>>>>>
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