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Export data from Nebula Graph

This topic uses an example to illustrate how to use Exchange to export data from Nebula Graph to a CSV file.

Enterpriseonly

Only Exchange Enterprise Edition supports exporting data from Nebula Graph to a CSV file.

Note

SSL encryption is not supported when exporting data from Nebula Graph.

Preparation

This example is completed on a virtual machine equipped with Linux. The hardware and software you need to prepare before exporting data are as follows.

Hardware

Type Information
CPU 4 Intel(R) Xeon(R) Platinum 8260 CPU @ 2.30GHz
Memory 16G
Hard disk 50G

System

CentOS 7.9.2009

Software

Name Version
JDK 1.8.0
Hadoop 2.10.1
Scala 2.12.11
Spark 2.4.7
Nebula Graph 3.2.0

Dataset

As the data source, Nebula Graph stores the basketballplayer dataset in this example, the Schema elements of which are shown as follows.

Element Name Property
Tag player name string, age int
Tag team name string
Edge type follow degree int
Edge type serve start_year int, end_year int

Steps

  1. Get the JAR file of Exchange Enterprise Edition from the Nebula Graph Enterprise Edition Package.

  2. Modify the configuration file.

    Exchange Enterprise Edition provides the configuration template export_application.conf for exporting Nebula Graph data. For details, see Exchange parameters. The core content of the configuration file used in this example is as follows:

    ...
    
      # Processing tags
      # There are tag config examples for different dataSources.
      tags: [
        # export NebulaGraph tag data to csv, only support export to CSV for now.
        {
          name: player
          type: {
            source: Nebula
            sink: CSV
          }
          # the path to save the NebulaGrpah data, make sure the path doesn't exist.
          path:"hdfs://192.168.8.177:9000/vertex/player"
          # if no need to export any properties when export NebulaGraph tag data
          # if noField is configured true, just export vertexId
          noField:false
          # define properties to export from NebulaGraph tag data
          # if return.fields is configured as empty list, then export all properties
          return.fields:[]
          # nebula space partition number
          partition:10
        }
    
    ...
    
      ]
    
      # Processing edges
      # There are edge config examples for different dataSources.
      edges: [
        # export NebulaGraph tag data to csv, only support export to CSV for now.
        {
          name: follow
          type: {
            source: Nebula
            sink: CSV
          }
          # the path to save the NebulaGrpah data, make sure the path doesn't exist.
          path:"hdfs://192.168.8.177:9000/edge/follow"
          # if no need to export any properties when export NebulaGraph edge data
          # if noField is configured true, just export src,dst,rank
          noField:false
          # define properties to export from NebulaGraph edge data
          # if return.fields is configured as empty list, then export all properties
          return.fields:[]
          # nebula space partition number
          partition:10
        }
    
    ...
    
      ]
    }
    
  3. Export data from Nebula Graph with the following command.

    <spark_install_path>/bin/spark-submit --master "local" --class com.vesoft.nebula.exchange.Exchange nebula-exchange-x.y.z.jar_path> -c <export_application.conf_path>
    

    The command used in this example is as follows.

    $ ./spark-submit --master "local" --class com.vesoft.nebula.exchange.Exchange \
      ~/exchange-ent/nebula-exchange-ent-3.0.0.jar -c ~/exchange-ent/export_application.conf
    
  4. Check the exported data.

    1. Check whether the CSV file is successfully generated under the target path.

      $ hadoop fs -ls /vertex/player
      Found 11 items
      -rw-r--r--   3 nebula supergroup          0 2021-11-05 07:36 /vertex/player/_SUCCESS
      -rw-r--r--   3 nebula supergroup        160 2021-11-05 07:36 /vertex/player/    part-00000-17293020-ba2e-4243-b834-34495c0536b3-c000.csv
      -rw-r--r--   3 nebula supergroup        163 2021-11-05 07:36 /vertex/player/    part-00001-17293020-ba2e-4243-b834-34495c0536b3-c000.csv
      -rw-r--r--   3 nebula supergroup        172 2021-11-05 07:36 /vertex/player/    part-00002-17293020-ba2e-4243-b834-34495c0536b3-c000.csv
      -rw-r--r--   3 nebula supergroup        172 2021-11-05 07:36 /vertex/player/    part-00003-17293020-ba2e-4243-b834-34495c0536b3-c000.csv
      -rw-r--r--   3 nebula supergroup        144 2021-11-05 07:36 /vertex/player/    part-00004-17293020-ba2e-4243-b834-34495c0536b3-c000.csv
      -rw-r--r--   3 nebula supergroup        173 2021-11-05 07:36 /vertex/player/    part-00005-17293020-ba2e-4243-b834-34495c0536b3-c000.csv
      -rw-r--r--   3 nebula supergroup        160 2021-11-05 07:36 /vertex/player/    part-00006-17293020-ba2e-4243-b834-34495c0536b3-c000.csv
      -rw-r--r--   3 nebula supergroup        148 2021-11-05 07:36 /vertex/player/    part-00007-17293020-ba2e-4243-b834-34495c0536b3-c000.csv
      -rw-r--r--   3 nebula supergroup        125 2021-11-05 07:36 /vertex/player/    part-00008-17293020-ba2e-4243-b834-34495c0536b3-c000.csv
      -rw-r--r--   3 nebula supergroup        119 2021-11-05 07:36 /vertex/player/    part-00009-17293020-ba2e-4243-b834-34495c0536b3-c000.csv
      
    2. Check the contents of the CSV file to ensure that the data export is successful.


Last update: August 12, 2022