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我正在使用海王星的图形数据库和通过 python 的 gremlin 查询，将地址存储在数据库中。大多数查询执行良好，但一旦我尝试以下查询海王星返回内部失败异常：

g.V(address).outE('isPartOf').inV().
  dedup().as_('groupNode').
  inE('isPartOf').outV().dedup().as_('children').
  addE('isPartOf').to(group).
  select('groupNode').drop().
  fold().
  coalesce(__.unfold(), 
           g.V(address).addE('isPartOf').to(group)).next()

每个地址都有可能属于一个组。当地址已经分配给一个组时，我尝试获取分配给该组的所有地址并将它们分配给一个新组，同时删除旧组。如果地址尚未分配给组，我只想立即将地址分配给新组。

如果我自己尝试这个查询，一切都会完美执行（尽管查询有点慢）。但是，一旦我尝试在更多地址上并行执行此查询，此查询将失败并出现以下错误：

Traceback (most recent call last):
  File "/usr/lib64/python2.7/threading.py", line 804, in __bootstrap_inner
    self.run()
  File "gremlinExample.py", line 30, in run
    processTx(self.tx, self.g, self.parentBlock)
  File "gremlinExample.py", line 152, in processTx
    g.V(address).outE('isPartOf').inV().dedup().as_('groupNode').inE('isPartOf').outV().dedup().as_('children').select('children').addE('isPartOf').to(group).select('groupNode').drop().fold().coalesce(__.unfold(), g.V(address).addE('isPartOf').to(group)).next()
  File "/home/ec2-user/.local/lib/python2.7/site-packages/gremlin_python/process/traversal.py", line 70, in next
    return self.__next__()
  File "/home/ec2-user/.local/lib/python2.7/site-packages/gremlin_python/process/traversal.py", line 43, in __next__
    self.traversal_strategies.apply_strategies(self)
  File "/home/ec2-user/.local/lib/python2.7/site-packages/gremlin_python/process/traversal.py", line 346, in apply_strategies
    traversal_strategy.apply(traversal)
  File "/home/ec2-user/.local/lib/python2.7/site-packages/gremlin_python/driver/remote_connection.py", line 143, in apply
    remote_traversal = self.remote_connection.submit(traversal.bytecode)
  File "/home/ec2-user/.local/lib/python2.7/site-packages/gremlin_python/driver/driver_remote_connection.py", line 54, in submit
    results = result_set.all().result()
  File "/usr/lib/python2.7/site-packages/concurrent/futures/_base.py", line 405, in result
    return self.__get_result()
  File "/usr/lib/python2.7/site-packages/concurrent/futures/_base.py", line 357, in __get_result
    raise type(self._exception), self._exception, self._traceback
GremlinServerError: 500: {"requestId":"a42015b7-6b22-4bd1-9e7d-e3252e8f3ab6","code":"InternalFailureException","detailedMessage":"Can not get the attachable from the host vertex: v[64b32957-ef71-be47-c8d7-0109cfc4d9fd]-/->neptunegraph[org.apache.commons.configuration.PropertiesConfiguration@6db0f02]"}

据我所知，并行执行不应该是问题，因为每个查询都只是在数据库中排队（正是出于这个原因，我试图创建一个一次执行整个任务的查询）。

任何英语不好的借口，这不是我的母语

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1 回答 1

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对于其他在这里寻找更新的人 - OP 能够通过将 .next() 替换为 .iterate() 来解决问题。需要进行一些后续工作才能更好地理解查询和数据，但 OP 已放弃该项目并转向另一个解决方案。

于 2019-06-18T06:22:16.517 回答