Thank you Riccardo, that works (when moving the NOT before the IN : WHERE
#9:1 NOT IN). It does what I need.
One more question: with this solution, the SELECT is always done. So in
terms of performance, is it better to run the SELECT and then run the
CREATE if the result is not null or the CREATE FROM SELECT as you suggest
is equivalent or even better ?
Cheers,
Alain
Le mardi 17 février 2015 09:01:34 UTC+1, Riccardo Tasso a écrit :
>
> Hi, what about something like:
>
> CREATE EDGE knows FROM ( SELECT FROM #9:0 WHERE *NOT #9:1 IN out('knows')*
> ) TO #9:1
>
> Cheers,
> Riccardo
>
> 2015-02-16 18:41 GMT+01:00 Alain <[email protected] <javascript:>>:
>
>> Hi,
>> I've started using OrientDB (version 2.0.2, remote protocol) last week. I
>> have the exact same need as Dan (using ligthweight edges, no need for
>> properties).
>> However I believe the query that you suggested doesn't answer to the need
>> as it prevents from creating more than one 'knows' edge per 'user' vertex
>> however the goal is to prevent duplicate edges between 2 users (as in "one
>> user can only be friend once with another user but can have several
>> friends"). With your query, #9:0 can only have one 'knows'.
>>
>> Do you have any other suggestion (other than creating constraints) ?
>>
>> Thank you for your help.
>>
>> Cheers,
>> Alain
>>
>>
>> Le mercredi 7 janvier 2015 10:34:36 UTC+1, Riccardo Tasso a écrit :
>>>
>>> I would use the following query:
>>>
>>> CREATE EDGE knows FROM (SELECT FROM #9:0 WHERE out('knows') IS NULL) TO
>>> #9:1
>>>
>>> In this way you won't have any exception if the edge already exists, but
>>> it won't be inserted a duplicate.
>>>
>>> Cheers,
>>> Riccardo
>>>
>>> 2015-01-07 9:50 GMT+01:00 Dan Andrei <[email protected]>:
>>>
>>>> Hello, I've looked for some info but I couldn't find anything clearly
>>>> explained. My question is
>>>>
>>>> *How do I make a Edge unique in Orientdb ? version 1.7*
>>>>
>>>> The solution that I came up with:
>>>>
>>>> - delete the edge
>>>> - create it again
>>>>
>>>> but it's not nice. Edge is without any properties.
>>>>
>>>> *Example:*
>>>>
>>>> create edge is_friend from #12:0 to #12:3
>>>>
>>>> and if I call it again, there should be an error like when you make a
>>>> unique index.
>>>>
>>>> Lvca said Create a constraint on Edge out and in fields.
>>>>
>>>> But how exactly to do it ? I have a simple database with users and
>>>> edges "is_friend" from user to user without any additional properties on
>>>> the edge.
>>>>
>>>>
>>>>
>>>>
>>>> http://www.orientechnologies.com/docs/last/orientdb.wiki/
>>>> Graph-Schema.html#constraints
>>>>
>>>>
>>>>
>>>> Thank you very much
>>>>
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>>>>
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>>>
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