How do you make in Orientdb the edge to be unique

问题

How do I make a Edge unique in Orientdb.

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.

Thank you

回答1:

Create a constraint on Edge out and in fields. For more information:

http://www.orientechnologies.com/docs/last/orientdb.wiki/Graph-Schema.html#constraints

In your case try this:

CREATE INDEX UniqueEdges ON is_friend (out, in) unique

来源：https://stackoverflow.com/questions/27768489/how-do-you-make-in-orientdb-the-edge-to-be-unique