Crash - probably a bad query?

[clanstyles]

I'm using the dbpedia dataset and bulk loaded article_categories_en.ttl.bz2

wget http://downloads.dbpedia.org/3.9/en/article_categories_en.ttl.bz2
bzip2 -d article_categories_en.ttl.bz2 && gzip article_categories_en.ttl

Then I bulk loaded the data into a fresh dgraph db.

dgraphloader -r article_categories_en.ttl.gz

I tried to understand how the data was imported. I tried to describe the schema via

schema {
}

which renders

{
  "schema": [
    {
      "predicate": "_uid_",
      "type": "default"
    },
    {
      "predicate": "_predicate_",
      "type": "default"
    },
    {
      "predicate": "http://purl.org/dc/terms/subject",
      "type": "uid"
    }
  ]
}

This layout looks quite odd to me. I've been trying to figure out how to do anything with it, even query it. I ran the query:

{
  _predicate_(func:anyoftext(_predicate_, "something")) {
    
  }
}

which causes:

2017/06/11 04:53:12 lists.go:284: Dirty map size: 0
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0xc5a5cc]

goroutine 7037 [running]:
github.com/dgraph-io/dgraph/worker.processTask(0x7fa988360050, 0xc541b9a6c0, 0xc42010a380, 0x1, 0x0, 0x0, 0x0)
	/home/travis/gopath/src/github.com/dgraph-io/dgraph/worker/task.go:197 +0x17c
github.com/dgraph-io/dgraph/worker.ProcessTaskOverNetwork(0x7fa988360050, 0xc541b9a6c0, 0xc42010a380, 0x0, 0x0, 0x0)
	/home/travis/gopath/src/github.com/dgraph-io/dgraph/worker/task.go:60 +0x87a
github.com/dgraph-io/dgraph/query.ProcessGraph(0x1739ec0, 0xc541b9a6c0, 0xc420151680, 0x0, 0xc541b9a720)
	/home/travis/gopath/src/github.com/dgraph-io/dgraph/query/query.go:1621 +0x20fd
created by github.com/dgraph-io/dgraph/query.ProcessQuery
	/home/travis/gopath/src/github.com/dgraph-io/dgraph/query/query.go:1248 +0x70c

as a side note why should you be allowed to import a quad with a name that is a link, which contains invalid characters you can't even query?

[ashwin95r]

The crash was due to a nil list and has been fixed.

@clanstyles Regarding the usage of a link as a predicate, it has to be done with <>. For example:

{
  me(id: <http://dbpedia.org/resource/Albedo>) {
    <http://purl.org/dc/terms/subject> {
      _uid_
    }
  }
}

retrurns

{
  "me": [
    {
      "_uid_": "0x4339",
      "http://purl.org/dc/terms/subject": [
        {
          "_uid_": "0x2bae"
        },
        {
          "_uid_": "0x424e"
        },
        {
          "_uid_": "0x57bb"
        },
        {
          "_uid_": "0x5afc"
        },
        {
          "_uid_": "0x8ae4"
        },
        {
          "_uid_": "0xc0dc"
        }
      ]
    }
  ],
  "server_latency": {
    "json": "687µs",
    "parsing": "842µs",
    "processing": "551µs",
    "total": "2ms"
  }
}