CODEWITHSUNDEEP
neo4j
manu
manu

Reputation: 1453

unexpected failure on unique constraint in neo4j

I'm trying to load some data into neo4j from csv files, and it seems a unique constraint error is triggered when it shouldn't. In particular, I created a contraint using

CREATE CONSTRAINT ON (node:`researcher`) ASSERT node.`id_patstats` IS UNIQUE;

Then, after inserting some data in neo4j, if I run (in neo4j browser)

MATCH (n:researcher {id_patstats: "2789"})
RETURN n

I get no results (no changes, no records), but if I run

USING PERIODIC COMMIT
LOAD CSV WITH HEADERS FROM
'file:///home/manu/proyectos/PTL_RDIgraphs/rdigraphs/datamanager/tmp_patents/person906.csv' AS line
MERGE (n:researcher {`name` : line.`person_name`})
SET n.`id_patstats` = line.`person_id`;

I get

Neo.ClientError.Schema.ConstraintValidationFailed: Node(324016) already exists with label researcher and property id_patstats = '2789'

and the content of file person906.csv is

manu@cochi tmp_patents $cat person906.csv
person_id,person_name,doc_std_name,doc_std_name_id
2789,"li, jian",LI JIAN,2390

(this a minimum non working example extracted from a larger dataset; also, in the original "person906.csv" I made sure that "id_patstats" is really unique).

Any clue?

EDIT:

Still struggling with this...

If I run

MATCH (n) 
WHERE EXISTS(n.id_patstats) 
RETURN DISTINCT "node" as entity, n.id_patstats AS id_patstats 
LIMIT 25 
UNION ALL 
MATCH ()-[r]-() 
WHERE EXISTS(r.id_patstats) 
RETURN DISTINCT "relationship" AS entity, r.id_patstats AS id_patstats 
LIMIT 25

(clicking in the neo4j browser to get some examples of the id_patstats property) I get

(no changes, no records)

that is, id_patstats property is not set anywhere. Moreover

MATCH (n:researcher {`name` : "li, jian"})
SET n.`id_patstats` = XXX;

this will always trigger an error regardless of XXX, which (I guess) means the actual problem is that the name "li, jian" is already present. Although I didn't set any constraint on the name property, I'm guessing neo4j goes like this: you are trying to set a UNIQUE property on a node matching a property (name) that is not necessarily UNIQUE; hence that match could yield several nodes and I can't set the same UNIQUE property on all of them...so I won't even try

Upvotes: 2

Views: 2210

Answers (1)

Tomaž Bratanič
Tomaž Bratanič

Reputation: 6514

At least two of your researchers have the same name. You shouldn't MERGE by name and then add id as a property. You should MERGE by id and add the name as a property and it will work fine.

USING PERIODIC COMMIT
LOAD CSV WITH HEADERS FROM
'file:///home/manu/proyectos/PTL_RDIgraphs/rdigraphs/datamanager/tmp_patents/person906.csv' AS line
MERGE (n:researcher {`id_patstats`:line.`person_id`})
SET n.name`=line.`person_name`;

Upvotes: 1

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