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I was using the wrong class to load the module. The following code works:

OLAP based Gremlin traversals will be much slower than standard OLTP traversals even for small datasets. There is considerable cost just in getting Spark primed up to process your traversal. That overhead alone might easily give your OLAP query a 1 minute handicap over OLTP. In the comments to your question you explained that your query is taking around six minutes. That does seem a bit on the long side but maybe in the realm of normal for OLAP depending on your environment??

Some graph will optimize for an OLAP count() and get you a pretty speedy result but you tagged this question with "JanusGraph" so I don't think that applies here.

You typically don't see the value of OLAP based traversals until you start concerning yourself with large scale graphs. Compare counting 100+ million edges in OLAP versus OLTP and you probably won't mind waiting six minutes for an answer at all (as OLTP might not finish at all).

It's hard to say what you might do to make your current setup faster as you are really just proving things work at this point. Now that you have a working model, I would suggest that the next step would be to generate a significantly larger graph (10 million vertices maybe) and try your count again with a decent sized spark cluster.

Are you running this into a Databricks instance? If not, that's the problem: dbutils are provided by Databricks execution context. In that case, as far as I know, you have three options:

1. Package your application into a jar file and run it using a Databricks job
2. Use databricks-connect

3. Try to emulate a mocked dbutils instance outside Databricks as shown here:

That error occurs when the input field of your dataframe for which you want to apply the StringIndexer transformation is a Vector. In the Spark documentation https://spark.apache.org/docs/latest/ml-features#stringindexer you can see that the input column is a string. This transformer performs a distinct to that column and creates a new column with integers that correspond to each different string value. It does not work for vectors.