为什么顶点不会随着 g.V().drop() 下降？

Question

问题

你如何用GraphTraversalSource g

清理

顶点（和边）？

我不明白为什么

g.V().drop()

不能与

traversal().withRemote()

一起工作 当我与

OrientGraph.traversal()

一起工作时。
我如何

drop()

顶点与

GraphTraversalSource g

？

GraphTraversalSource g = traversal().withRemote("conf/remote-graph.properties");

OrientGraph orientGraph = OrientGraph.open(configuration);
GraphTraversalSource g = orientGraph.traversal();

繁殖

步骤

1. 创建和启动JanusGraph [Docker-container]

   docker run -d -p 8182:8182 janusgraph/janusgraph
   

2. 在 Java 项目中运行

   drop()

3. 结果
   1. Expect：顶点被丢弃。

      g.V().count().next()

      等于 2.
   2. 实际：顶点没有被丢弃。

      g.V().count().next()

      增加 2.

日志

我已经尝试过将

.next()

附加到几乎所有内容上。

g.V().drop().next()

原因

Exception in thread "main" java.util.NoSuchElementException

2023-05-04 08:08:03,834 [INFO] [c.j.m.Manifests.gremlin-driver-loop-1] ::    0 attributes loaded from 97 stream(s) in 20ms, 57 saved, 1788 ignored: []
2023-05-04 08:08:03,909 [INFO] [o.a.t.g.d.Connection.gremlin-driver-conn-scheduler-1] ::     Created new connection for ws://localhost:8182/gremlin
2023-05-04 08:08:03,909 [INFO] [o.a.t.g.d.Connection.gremlin-driver-conn-scheduler-2] ::     Created new connection for ws://localhost:8182/gremlin
2023-05-04 08:08:03,910 [INFO] [o.a.t.g.d.ConnectionPool.gremlin-driver-host-scheduler-1] ::     Opening connection pool on Host{address=localhost/127.0.0.1:8182, hostUri=ws://localhost:8182/gremlin} with core size of 2
Exception in thread "main" java.util.NoSuchElementException
    at org.apache.tinkerpop.gremlin.driver.ResultSet$1.next(ResultSet.java:187)
    at org.apache.tinkerpop.gremlin.driver.ResultSet$1.next(ResultSet.java:169)
    at org.apache.tinkerpop.gremlin.driver.remote.DriverRemoteTraversal$TraverserIterator.next(DriverRemoteTraversal.java:115)
    at org.apache.tinkerpop.gremlin.driver.remote.DriverRemoteTraversal$TraverserIterator.next(DriverRemoteTraversal.java:100)
    at org.apache.tinkerpop.gremlin.driver.remote.DriverRemoteTraversal.nextTraverser(DriverRemoteTraversal.java:92)
    at org.apache.tinkerpop.gremlin.process.remote.traversal.step.map.RemoteStep.processNextStart(RemoteStep.java:80)
    at org.apache.tinkerpop.gremlin.process.traversal.step.util.AbstractStep.next(AbstractStep.java:135)
    at org.apache.tinkerpop.gremlin.process.traversal.step.util.AbstractStep.next(AbstractStep.java:40)
    at org.apache.tinkerpop.gremlin.process.traversal.util.DefaultTraversal.next(DefaultTraversal.java:249)
    at Main.main(Main.java:15)

代码

│   pom.xml
│
├───src
│   ├───main
│   │   ├───java
│   │   │       Main.java
│   │   │
│   │   └───resources
│   │       │   log4j2.xml
│   │       │
│   │       ├───conf
│   │       │       remote-graph.properties
│   │       │       remote-objects.yaml

Main.java

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.Transaction;
import org.apache.tinkerpop.gremlin.structure.Vertex;

import static org.apache.tinkerpop.gremlin.process.traversal.AnonymousTraversalSource.traversal;

public class Main {
    private static final Logger logger = LogManager.getLogger(Main.class);
    public static void main(String[] args) throws Exception {
        GraphTraversalSource g = traversal().withRemote("conf/remote-graph.properties");
        Transaction tx = g.tx();
        tx.open();
        g.V().drop();
//        tx.commit();
//        tx = g.tx();
        Vertex v1 = g.addV("person").property("name","marko").next();
        Vertex v2 = g.addV("person").property("name","stephen").next();
        g.V(v1).addE("knows").to(v2).property("weight",0.75).iterate();
        tx.commit();
        logger.info("g.V().count().next():\t" + g.V().count().next());
        g.close();
    }
}

remote-graph.properties

gremlin.remote.remoteConnectionClass=org.apache.tinkerpop.gremlin.driver.remote.DriverRemoteConnection
gremlin.remote.driver.clusterFile=src/main/resources/conf/remote-objects.yaml
gremlin.remote.driver.sourceName=g

remote-objects.yaml

hosts: [localhost]
port: 8182
serializer: {
  className: org.apache.tinkerpop.gremlin.driver.ser.GraphBinaryMessageSerializerV1,
  config: { ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry] }
}

pom.xml

    <dependencies>
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-slf4j2-impl</artifactId>
            <version>2.20.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.tinkerpop</groupId>
            <artifactId>gremlin-core</artifactId>
            <version>3.6.2</version>
        </dependency>
        <dependency>
            <groupId>org.janusgraph</groupId>
            <artifactId>janusgraph-core</artifactId>
            <version>0.6.4-20230429-020227.dc3f877</version>
        </dependency>
    </dependencies>

Answer 1

gremlin 控制台自动尝试

next

遍历，直到达到配置的次数。 java程序中的遍历要生效，必须自己加上

iterate()

，所以

g.V().drop().iterate()

.