Hi,
you could start with something like:
select from (
select expand( in('D') ) from A where aField = 'a456'
) where in('D') contains ( cField = 'c123' )
The idea is: you start from A sub set and get all the incoming B vertices
(connected as IN with edge 'D'). Then you filter only the instances that
have incoming C vertices that are in the other subset.
Let me know if works.
Lvc@
On 24 January 2014 23:38, Nick Bauer <[email protected]> wrote:
> The graph looks like this:
>
> A <--- B ---> C
>
> Basically, I want to start with a subset of A vertices and a subset of C
> vertices, and I want to get back the subset of B vertices that is linked to
> at least 1 vertex in each of the starting subsets.
>
> I actually just tried combining the two queries above, which seems to work
> a lot better:
> select * from (
> traverse out from (
> traverse in_D from (
> select * from A where aField = 'a456'
> )
> )
> )
> where @class = 'B' and (
> out_D traverse(0,1) (
> @class = 'C' and cField = 'c123'
> )
> )
>
> Is there a better way to query for those B vertices?
>
> Thanks!
>
>
> On Friday, January 24, 2014 3:03:25 PM UTC-7, Lvc@ wrote:
>
>> Hi Nick,
>> can you explain your domain in terms of a graph? Like:
>>
>> A ---> B <---- C
>>
>> And where you start and what you want to get back?
>>
>> Lvc@
>>
>>
>>
>> On 24 January 2014 22:00, Nick Bauer <[email protected]> wrote:
>>
>>> We are using OrientDB 1.6.4.
>>>
>>> We have a graph with 3 classes of vertices: A, B, and C
>>> Class A has a medium multiplicity (tens of thousands of vertices)
>>> Class B has a high multiplicity (hundreds of thousands of vertices)
>>> Class C has a low multiplicity (a few vertices)
>>>
>>> We have also defined an edge class, D, which is used to link vertices of
>>> all three classes.
>>>
>>> Every instance of class B is linked to at least one instance of A and at
>>> least one instance of C. Also, the links from the B instances are fairly
>>> evenly distributed among all of the A instances and among all of the C
>>> instances.
>>>
>>> Thus, there are a relatively small number of B instances linked to any
>>> single A instance. There are a much higher number of B instances linked to
>>> any single C instance.
>>>
>>> We want to find all instances of class B that are linked to at least one
>>> A instance that has a certain field value and that are also linked to at
>>> least one instance of C that has a certain field value.
>>>
>>>
>>> We can solve half of the problem with a query like this, which traverses
>>> from the A instances that match the condition, and finds all of the B
>>> instances linked to them:
>>> select * from (traverse out from (traverse in_D from (select * from A
>>> where aField = 'a456') )) where @class = 'B'
>>>
>>> This query quickly returns a relatively small number of B instances to
>>> work with, so it seems beneficial to start there. However,
>>> from there, we can continue to traverse out to the C instances linked to
>>> those B instances, but it seems like if we do that, we lose the ability to
>>> further filter out those B instances based on the C instances they link to.
>>>
>>> Is there a way to filter the B instances based on the C instances they
>>> link to, without traversing to the C instances themselves?
>>>
>>> We have also found that this query works, but given the high
>>> multiplicity of class B, it seems to take a very long time (around 10
>>> minutes) to run:
>>> select from B where ((out_D traverse(0,1) (@class = 'C' and cField =
>>> 'c123')) and (out_D traverse(0,1) (@class = 'A' and aField = 'a456')))
>>>
>>> Is there a better way to query for vertices based on their links to
>>> multiple collections of vertices?
>>>
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