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Import data from CSV files

This topic provides an example of how to use Exchange to import Nebula Graph data stored in HDFS or local CSV files.

To import a local CSV file to Nebula Graph, see Nebula Importer.

Data set

This topic takes the basketballplayer dataset as an example.

Environment

This example is done on MacOS. Here is the environment configuration information:

  • Hardware specifications:
    • CPU: 1.7 GHz Quad-Core Intel Core i7
    • Memory: 16 GB
  • Spark: 2.4.7, stand-alone
  • Hadoop: 2.9.2, pseudo-distributed deployment

Prerequisites

Before importing data, you need to confirm the following information:

  • Nebula Graph has been installed and deployed with the following information:

    • IP addresses and ports of Graph and Meta services.
    • The user name and password with write permission to Nebula Graph.
  • Spark has been installed.
  • Learn about the Schema created in Nebula Graph, including names and properties of Tags and Edge types, and more.
  • If files are stored in HDFS, ensure that the Hadoop service is running normally.
  • If files are stored locally and Nebula Graph is a cluster architecture, you need to place the files in the same directory locally on each machine in the cluster.

Steps

Step 1: Create the Schema in Nebula Graph

Analyze the data to create a Schema in Nebula Graph by following these steps:

  1. Identify the Schema elements. The Schema elements in the Nebula Graph are shown in the following table.

    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
  2. Create a graph space basketballplayer in the Nebula Graph and create a Schema as shown below.

    ## Create a graph space.
    nebula> CREATE SPACE basketballplayer \
            (partition_num = 10, \
            replica_factor = 1, \
            vid_type = FIXED_STRING(30));
    
    ## Use the graph space basketballplayer.
    nebula> USE basketballplayer;
    
    ## Create the Tag player.
    nebula> CREATE TAG player(name string, age int);
    
    ## Create the Tag team.
    nebula> CREATE TAG team(name string);
    
    ## Create the Edge type follow.
    nebula> CREATE EDGE follow(degree int);
    
    ## Create the Edge type serve.
    nebula> CREATE EDGE serve(start_year int, end_year int);
    

For more information, see Quick start workflow.

Step 2: Process CSV files

Confirm the following information:

  1. Process CSV files to meet Schema requirements.

    Note

    Exchange supports uploading CSV files with or without headers.

  2. Obtain the CSV file storage path.

Step 3: Modify configuration files

After Exchange is compiled, copy the conf file target/classes/application.conf to set CSV data source configuration. In this example, the copied file is called csv_application.conf. For details on each configuration item, see Parameters in the configuration file.

{
  # Spark configuration
  spark: {
    app: {
      name: Nebula Exchange 3.0.0
    }
    driver: {
      cores: 1
      maxResultSize: 1G
    }
    executor: {
        memory:1G
    }

    cores: {
      max: 16
    }
  }

  # Nebula Graph configuration
  nebula: {
    address:{
      # Specify the IP addresses and ports for Graph and Meta services.
      # If there are multiple addresses, the format is "ip1:port","ip2:port","ip3:port".
      # Addresses are separated by commas.
      graph:["127.0.0.1:9669"]
      meta:["127.0.0.1:9559"]
    }

    # The account entered must have write permission for the Nebula Graph space.
    user: root
    pswd: nebula

    # Fill in the name of the graph space you want to write data to in the Nebula Graph.
    space: basketballplayer
    connection: {
      timeout: 3000
      retry: 3
    }
    execution: {
      retry: 3
    }
    error: {
      max: 32
      output: /tmp/errors
    }
    rate: {
      limit: 1024
      timeout: 1000
    }
  }

  # Processing vertexes
  tags: [
    # Set the information about the Tag player.
    {
      # Specify the Tag name defined in Nebula Graph.
      name: player
      type: {
        # Specify the data source file format to CSV.
        source: csv

        # Specify how to import the data into Nebula Graph: Client or SST.
        sink: client
      }

      # Specify the path to the CSV file.
      # If the file is stored in HDFS, use double quotation marks to enclose the file path, starting with hdfs://. For example: "hdfs://ip:port/xx/xx".
      # If the file is stored locally, use double quotation marks to enclose the file path, starting with file://. For example: "file:///tmp/xx.csv".
      path: "hdfs://192.168.*.*:9000/data/vertex_player.csv"

      # If the CSV file does not have a header, use [_c0, _c1, _c2, ..., _cn] to represent its header and indicate the columns as the source of the property values.
      # If the CSV file has headers, use the actual column names.
      fields: [_c1, _c2]

      # Specify the column names in the player table in fields, and their corresponding values are specified as properties in the Nebula Graph.
      # The sequence of fields and nebula.fields must correspond to each other.
      nebula.fields: [age, name]

      # Specify a column of data in the table as the source of vertex VID in the Nebula Graph.
      # The value of vertex must be the same as the column names in the above fields or csv.fields.
      # Currently, Nebula Graph 3.1.0 supports only strings or integers of VID.
      vertex: {
        field:_c0
        # policy:hash
      }

      # The delimiter specified. The default value is comma.
      separator: ","

      # If the CSV file has a header, set the header to true.
      # If the CSV file does not have a header, set the header to false. The default value is false.
      header: false

      # The number of data written to Nebula Graph in a single batch.
      batch: 256

      # The number of Spark partitions.
      partition: 32
    }

    # Set the information about the Tag Team.
    {
      # Specify the Tag name defined in Nebula Graph.
      name: team
      type: {
        # Specify the data source file format to CSV.
        source: csv

        # Specify how to import the data into Nebula Graph: Client or SST.
        sink: client
      }

      # Specify the path to the CSV file.
      # If the file is stored in HDFS, use double quotation marks to enclose the file path, starting with hdfs://. For example: "hdfs://ip:port/xx/xx".
      # If the file is stored locally, use double quotation marks to enclose the file path, starting with file://. For example: "file:///tmp/xx.csv".
      path: "hdfs://192.168.*.*:9000/data/vertex_team.csv"

      # If the CSV file does not have a header, use [_c0, _c1, _c2, ..., _cn] to represent its header and indicate the columns as the source of the property values.
      # If the CSV file has headers, use the actual column names.
      fields: [_c1]

      # Specify the column names in the player table in fields, and their corresponding values are specified as properties in the Nebula Graph.
      # The sequence of fields and nebula.fields must correspond to each other.
      nebula.fields: [name]

      # Specify a column of data in the table as the source of VIDs in the Nebula Graph.
      # The value of vertex must be the same as the column names in the above fields or csv.fields.
      # Currently, Nebula Graph 3.1.0 supports only strings or integers of VID.
      vertex: {
        field:_c0
        # policy:hash
      }

      # The delimiter specified. The default value is comma.
      separator: ","

      # If the CSV file has a header, set the header to true.
      # If the CSV file does not have a header, set the header to false. The default value is false.
      header: false

      # The number of data written to Nebula Graph in a single batch.
      batch: 256

      # The number of Spark partitions.
      partition: 32
    }


    # If more vertexes need to be added, refer to the previous configuration to add them.
  ]
  # Processing edges
  edges: [
    # Set the information about the Edge Type follow.
    {
      # Specify the Edge Type name defined in Nebula Graph.
      name: follow
      type: {
        # Specify the data source file format to CSV.
        source: csv

        # Specify how to import the data into Nebula Graph: Client or SST.
        sink: client
      }

      # Specify the path to the CSV file.
      # If the file is stored in HDFS, use double quotation marks to enclose the file path, starting with hdfs://. For example: "hdfs://ip:port/xx/xx".
      # If the file is stored locally, use double quotation marks to enclose the file path, starting with file://. For example: "file:///tmp/xx.csv".
      path: "hdfs://192.168.*.*:9000/data/edge_follow.csv"

      # If the CSV file does not have a header, use [_c0, _c1, _c2, ..., _cn] to represent its header and indicate the columns as the source of the property values.
      # If the CSV file has headers, use the actual column names.
      fields: [_c2]

      # Specify the column names in the edge table in fields, and their corresponding values are specified as properties in the Nebula Graph.
      # The sequence of fields and nebula.fields must correspond to each other.
      nebula.fields: [degree]

      # Specify a column as the source for the source and destination vertexes.
      # The value of vertex must be the same as the column names in the above fields or csv.fields.
      # Currently, Nebula Graph 3.1.0 supports only strings or integers of VID.
      source: {
        field: _c0
      }
      target: {
        field: _c1
      }

      # The delimiter specified. The default value is comma.
      separator: ","

      # Specify a column as the source of the rank (optional).

      #ranking: rank

      # If the CSV file has a header, set the header to true.
      # If the CSV file does not have a header, set the header to false. The default value is false.
      header: false

      # The number of data written to Nebula Graph in a single batch.
      batch: 256

      # The number of Spark partitions.
      partition: 32
    }

    # Set the information about the Edge Type serve.
    {
      # Specify the Edge Type name defined in Nebula Graph.
      name: serve
      type: {
        # Specify the data source file format to CSV.
        source: csv

        # Specify how to import the data into Nebula Graph: Client or SST.
        sink: client
      }

      # Specify the path to the CSV file.
      # If the file is stored in HDFS, use double quotation marks to enclose the file path, starting with hdfs://. For example: "hdfs://ip:port/xx/xx".
      # If the file is stored locally, use double quotation marks to enclose the file path, starting with file://. For example: "file:///tmp/xx.csv".
      path: "hdfs://192.168.*.*:9000/data/edge_serve.csv"

      # If the CSV file does not have a header, use [_c0, _c1, _c2, ..., _cn] to represent its header and indicate the columns as the source of the property values.
      # If the CSV file has headers, use the actual column names.
      fields: [_c2,_c3]

      # Specify the column names in the edge table in fields, and their corresponding values are specified as properties in the Nebula Graph.
      # The sequence of fields and nebula.fields must correspond to each other.
      nebula.fields: [start_year, end_year]

      # Specify a column as the source for the source and destination vertexes.
      # The value of vertex must be the same as the column names in the above fields or csv.fields.
      # Currently, Nebula Graph 3.1.0 supports only strings or integers of VID.
      source: {
        field: _c0
      }
      target: {
        field: _c1
      }

      # The delimiter specified. The default value is comma.
      separator: ","

      # Specify a column as the source of the rank (optional).
      #ranking: _c5

      # If the CSV file has a header, set the header to true.
      # If the CSV file does not have a header, set the header to false. The default value is false.
      header: false

      # The number of data written to Nebula Graph in a single batch.
      batch: 256

      # The number of Spark partitions.
      partition: 32
    }

  ]
    # If more edges need to be added, refer to the previous configuration to add them.
}

Step 4: Import data into Nebula Graph

Run the following command to import CSV data into Nebula Graph. For descriptions of the parameters, see Options for import.

${SPARK_HOME}/bin/spark-submit --master "local" --class com.vesoft.nebula.exchange.Exchange <nebula-exchange-3.0.0.jar_path> -c <csv_application.conf_path> 

Note

JAR packages are available in two ways: compiled them yourself, or download the compiled .jar file directly.

For example:

${SPARK_HOME}/bin/spark-submit  --master "local" --class com.vesoft.nebula.exchange.Exchange  /root/nebula-exchange/nebula-exchange/target/nebula-exchange-3.0.0.jar  -c /root/nebula-exchange/nebula-exchange/target/classes/csv_application.conf

You can search for batchSuccess.<tag_name/edge_name> in the command output to check the number of successes. For example, batchSuccess.follow: 300.

Step 5: (optional) Validate data

Users can verify that data has been imported by executing a query in the Nebula Graph client (for example, Nebula Studio). For example:

GO FROM "player100" OVER follow;

Users can also run the SHOW STATS command to view statistics.

Step 6: (optional) Rebuild indexes in Nebula Graph

With the data imported, users can recreate and rebuild indexes in Nebula Graph. For details, see Index overview.


Last update: May 9, 2022