Duplicate documents getting inserted in edge collection

Question

I am using node driver version 6 of arangodb to insert relations between two vertices as follows.

db.collection("starks").save({ 
    _from: "Starks/Lyanna-Stark", 
    _to: "Starks/Ned-Stark", 
    type: "married" 
});

This inserts relation married between Starks/Lyanna-Stark and Starks/Ned-Stark into the database. But when I run this query twice, it is inserting it two times with different relation key. I want to avoid this as only one entry should be present for a single relation. How can I achieve this ?

molecule · Accepted Answer · 2018-08-20T07:05:31.137

8

Just create a unique index for all the relations that you are creating. For example, if the name of your relation collection is relations, then run this query to make the combination of "_from", "_to", "type" as unique

db.relations.ensureIndex({ 
    type: "hash", 
    fields: [ "_from", "_to", "type" ], 
    unique: true 
});

Here is the link for reference https://docs.arangodb.com/3.0/Manual/Indexing/Hash.html#ensure-uniqueness-of-relations-in-edge-collections

edited Aug 20 '18 at 07:05

answered Aug 18 '18 at 13:41

molecule

883
1
12
25

Just a fix, if the collection name is ```relations``` then query should also be ```db.relations.ensureIndex({ ... }); ``` :P – Saif Ali Khan Aug 18 '18 at 14:37

score 0 · Answer 2 · answered Sep 29 '18 at 15:30

You are facing this problem for the simple fact that Arango is creating a new ID for everytime you save the object. The uniqueness of an edge record is achieved by the "_key" key.

In order to do so, you can either provide the "_key" key yourself, or you can alter the logic of your code to check if the record is already present in the db or not.

Duplicate documents getting inserted in edge collection

2 Answers2