Mark, thank you for posting the article! very interesting.
One more question, say i create a unique constraint on :State(name)
So, theoretically i shouldnt get duplicates, however, what happens when i
have the following query executed 2 times, simultaneously
MERGE (s:State {name: "Texas"})
CREATE UNIQUE s-[:city]->(c:City {name: "Houston"})
i would not want to create a unique constraint on :City(name), as obviously
multiple cities, in different states, can have the same name,
however , i would want to make sure that "Texas" would not have 2
"Houston"'s
how would this be accomplished?
On Monday, December 23, 2013 7:37:59 AM UTC-6, Mark Needham wrote:
>
> Hi,
>
> We were exploring a similar thing last week. I've written it up here -
> http://www.markhneedham.com/blog/2013/12/23/neo4j-cypher-using-merge-with-schema-indexesconstraints/
>
> But as Michael says, unique constraint is the way to go for this type of
> thing but once a Member is created with a specific id then merging on it
> will not create a duplicate node even if you're only using a non-unique
> index.
>
> Mark
>
> On Monday, 23 December 2013 01:00:34 UTC, Javad Karabi wrote:
>>
>> if i have 2 cypher query posts to neo4j
>>
>> "MERGE a:Member( {id: {member_id} })" , member_id: 5
>>
>> "MERGE a:Member( {id: {member_id} })" , member_id: 5
>>
>> with both of these posts occurring simultaneously, is it possible to have
>> 2 nodes created, instead of just the one?
>> that is, if the first merge was interrupted halfway though, and had not
>> completed yet, the second then creates a new one since it doesnt see the
>> first...
>> is this something that could potentially happen?
>>
>> on a related note, how would i enforce uniqueness on Member(id) ?
>>
>
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