How Do You Create Indexes In Java?

[ZachMurray]

Why is JanusGraph not recognizing the index I've made?

[WARN] [o.j.g.t.StandardJanusGraphTx.main] ::	 Query requires iterating over all vertices [[]]. For better performance, use indexes

I'm currently using a new and empty Cassandra [Docker container] so testing starts from a blank slate.
This output doesn't change regardless: if I add data in after or not, remove index creation line, or create a new Docker container.
I've been keeping the index in-between test-runs, so this shouldn't be an issue of delayed index creation.

2023-05-10 13:08:36,511 [INFO] [c.d.o.d.i.c.ContactPoints.main] ::	 Contact point localhost:19042 resolves to multiple addresses, will use them all ([localhost/127.0.0.1, localhost/0:0:0:0:0:0:0:1])
2023-05-10 13:08:36,652 [INFO] [c.d.o.d.i.c.DefaultMavenCoordinates.main] ::	 DataStax Java driver for Apache Cassandra(R) (com.datastax.oss:java-driver-core) version 4.15.0
2023-05-10 13:08:37,447 [INFO] [c.d.o.d.i.c.t.Clock.JanusGraph Session-admin-0] ::	 Using native clock for microsecond precision
2023-05-10 13:08:37,967 [WARN] [c.d.o.d.i.c.l.h.OptionalLocalDcHelper.JanusGraph Session-admin-0] ::	 [JanusGraph Session|default] You specified datacenter1 as the local DC, but some contact points are from a different DC: Node(endPoint=localhost/[0:0:0:0:0:0:0:1]:19042, hostId=null, hashCode=323b2632)=null; please provide the correct local DC, or check your contact points
2023-05-10 13:08:39,254 [INFO] [o.j.d.c.b.ReadConfigurationBuilder.main] ::	 Set default timestamp provider MICRO
2023-05-10 13:08:39,292 [INFO] [o.j.g.i.UniqueInstanceIdRetriever.main] ::	 Generated unique-instance-id=c0a8563c11216-rmt-lap-win201
2023-05-10 13:08:39,316 [INFO] [c.d.o.d.i.c.ContactPoints.main] ::	 Contact point localhost:19042 resolves to multiple addresses, will use them all ([localhost/127.0.0.1, localhost/0:0:0:0:0:0:0:1])
2023-05-10 13:08:39,365 [INFO] [c.d.o.d.i.c.t.Clock.JanusGraph Session-admin-0] ::	 Using native clock for microsecond precision
2023-05-10 13:08:39,441 [WARN] [c.d.o.d.i.c.l.h.OptionalLocalDcHelper.JanusGraph Session-admin-0] ::	 [JanusGraph Session|default] You specified datacenter1 as the local DC, but some contact points are from a different DC: Node(endPoint=localhost/127.0.0.1:19042, hostId=null, hashCode=27f6e3ea)=null; please provide the correct local DC, or check your contact points
2023-05-10 13:08:39,471 [INFO] [o.j.d.c.ExecutorServiceBuilder.main] ::	 Initiated fixed thread pool of size 40
2023-05-10 13:08:43,405 [INFO] [o.j.g.d.StandardJanusGraph.main] ::	 Gremlin script evaluation is disabled
2023-05-10 13:08:43,422 [INFO] [o.j.d.l.k.KCVSLog.main] ::	 Loaded unidentified ReadMarker start time 2023-05-10T18:08:43.422170Z into org.janusgraph.diskstorage.log.kcvs.KCVSLog$MessagePuller@37b52340
2023-05-10 13:08:44,856 [WARN] [o.j.g.t.StandardJanusGraphTx.main] ::	 Query requires iterating over all vertices [[]]. For better performance, use indexes
2023-05-10 13:08:44,874 [INFO] [Main.main] ::	 g.V().count().next():	0
2023-05-10 13:08:44,880 [WARN] [o.j.g.t.StandardJanusGraphTx.main] ::	 Query requires iterating over all vertices [[]]. For better performance, use indexes
2023-05-10 13:08:44,885 [WARN] [o.j.g.t.StandardJanusGraphTx.main] ::	 Query requires iterating over all vertices [[]]. For better performance, use indexes
2023-05-10 13:08:44,889 [INFO] [Main.main] ::	 g.V().count().next():	0

Process finished with exit code 0

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversalSource;
import org.apache.tinkerpop.gremlin.structure.Vertex;
import org.janusgraph.core.JanusGraph;
import org.janusgraph.core.JanusGraphFactory;
import org.janusgraph.core.JanusGraphVertex;
import org.janusgraph.core.PropertyKey;
import org.janusgraph.core.schema.JanusGraphManagement;

public class Test {
    private static final Logger logger = LogManager.getLogger(Main.class);

    public static void main(String[] args) {
        JanusGraph janusGraph = JanusGraphFactory.build().set("storage.backend", "cql").set("storage.hostname", "localhost:19042").open();
        JanusGraphManagement janusGraphManagement = janusGraph.openManagement();
        PropertyKey propertyKey = janusGraphManagement.getOrCreatePropertyKey("_id");
        if (!janusGraphManagement.containsGraphIndex("_id"))
            janusGraphManagement.buildIndex("_id", Vertex.class).addKey(propertyKey).buildCompositeIndex();
        janusGraphManagement.commit();
        GraphTraversalSource g = janusGraph.traversal();
        logger.info("g.V().count().next():\t" + g.V().count().next());
        g.V().drop().iterate();
        logger.info("g.V().count().next():\t" + g.V().count().next());
        janusGraph.close();
    }
}