Need some way preventing duplicate edges on the same pair of vertex.

[Mouri-Kogoro]

ArcadeDB Version: <version here, you can find it on the first line of server output>

JDK Version: OpenJDK 11

OS: Win7 64bit

Ex: When run this command "CREATE EDGE Own FROM aPerson TO aPet" multiple times, I don't want the DB create multiple 'Own' edges to the same pet. How can I do? I read the document but nowhere mentions about this.

[lvca]

@Mouri-Kogoro right now ArcadeDB doesn't support such constraint. What you can do is check if the vertices are already connected with:

boolean vertex1.isConnectedTo( vertex2 )

If not, you can create the edge. In a multi-thread context you can do this. In case a concurrent operation against the same vertices is executing, the transaction is repeated transparently (optimistic lock):

database.transaction( ()-> {
  if( !vertex1.isConnectedTo( vertex2 ) ){
    vertex1.newEdge( "Own", vertex2, true );
  }
});

[lvca]

@antarcticgiraffe we don't have anything in SQL like:

CREATE EDGE Own FROM aPerson TO aPet IF NOT EXISTS

Right?

[Mouri-Kogoro]

Thanks for reply. I hope in future, ArcadeDB team will consider to implement this feature, i.e. able to set 'no-duplicate' at type/class level. This will reduce a lot of programmer's burden for writing the check command or will prevent some query bugs that relate to counting edges/path.

[lvca]

I'd like to leave this issue for input about this feature. Implementing the syntax above is very easy, but what does IF NOT EXISTS mean? Is it about checking that the 2 vertices are not connected at all or are not connected with the Own type or perhaps with the same (optional) attributes?

[lvca]

Good news, I was able to implement this quite easily. There is a PR that once merged will allow to do this by:

• creating a unique index against Edge's @out and @in properties
• appending IF NOT EXISTS at the CREATE EDGE ... command

[lvca]

Merged. @Mouri-Kogoro please let us know if you can try this new feature, any feedback is welcome!

[Mouri-Kogoro]

Thank you for your great work! I'm happy to hear this good news. I'm quite busy with something else for now, I'll try this later. Anyway, I'm sure this feature will be useful for many ArcadeDB users.