Changing graph.set-vertex-id Property After Migration

[nikhilbonte21]

Current Scenario

• Source graph is running with graph.set-vertex-id=false (default), using JanusGraph-generated vertex IDs
• Created a migration script to replicate the existing graph
• Target graph set with graph.set-vertex-id=true to preserve source vertex IDs during migration
• Migration completed successfully with matching vertex IDs

Problem

1. Since graph.set-vertex-id is a GLOBAL_OFFLINE property, it cannot be modified at runtime
2. Application fails because JanusGraph expects user-specified vertex IDs with graph.set-vertex-id=true
3. Want to avoid implementing custom vertex ID generation logic

Reference

Found in documentation that graph.set-vertex-id can be modified using Gremlin console for existing graphs:
Custom Vertex IDs Documentation

Questions

1. Is it possible to change graph.set-vertex-id to false on the target graph after migration?

   • This would allow migration with custom IDs but then switch to JanusGraph-generated IDs for normal operation

2. If changing the property is possible, what are the risks of ID collisions?

   • Specifically between existing custom IDs and new JanusGraph-generated IDs

Any guidance or best practices would be appreciated.

Environment:

• JanusGraph version: 1.0.0
• Storage backend: Cassandra
• Index backend: Elasticsearch

[li-boxuan]

1. Yes
2. Risk of ID collision is the same as the risk pre-migration

[li-boxuan]

E.g. Assume I set Id = 4128 on the target graph when the flag is to true (allow custom IDs), is it fair to say when I update flag to false (JG to generate IDs) 4128 will never be generated by Janusgraph?

No.

But I thought in your scenario, you only set it to true for migration purpose (i.e. no "real" custom ID)?

[nikhilbonte21]

I create new graph with property to true so that I can replicate vertices with same IDs from my source graph
Once migrated, I plan to switch property to false so that JG will generate IDs for me.

So, what I get it that with this approach there is possibility of ID collision (between migrated IDs & JG generated IDs after migration), right?

[li-boxuan]

Wait, sorry I thought you were replicating the database. Apparently that's not the case, otherwise you wouldn't need to bother mutating this property.

In that case I think you might run into trouble. Let me check how bad it could be

[li-boxuan]

Okay I think this won't work. You cannot migrate this way.

[nikhilbonte21]

Thanks!

If Id collision is the only problem with this approach, I can try to handle it some how if possible.

Do you see any other problems?