Import data from Pulsar

This topic provides an example of how to use Exchange to import NebulaGraph data stored in Pulsar.

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

• NebulaGraph: 3.5.0. Deploy NebulaGraph with Docker Compose.

Prerequisites

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

• NebulaGraph 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 NebulaGraph.

• Exchange has been compiled, or download the compiled .jar file directly.

• Spark has been installed.

• Learn about the Schema created in NebulaGraph, including names and properties of Tags and Edge types, and more.

• The Pulsar service has been installed and started.

Precautions

• Only client mode is supported when importing Pulsar data, i.e. the value of parameters tags.type.sink and edges.type.sink is client.

• When importing Pulsar data, do not use Exchange version 3.4.0, which adds caching of imported data and does not support streaming data import. Use Exchange versions 3.0.0, 3.3.0, or 3.5.0.

Steps

Step 1: Create the Schema in NebulaGraph

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

1. Identify the Schema elements. The Schema elements in the NebulaGraph 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 NebulaGraph 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: Modify configuration files

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

{
  # Spark configuration
  spark: {
    app: {
      name: NebulaGraph Exchange 3.5.0
    }
    driver: {
      cores: 1
      maxResultSize: 1G
    }
    cores: {
      max: 16
    }
  }


  # NebulaGraph configuration
  nebula: {
    address:{
      # Specify the IP addresses and ports for Graph and all 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"]
      # the address of any of the meta services.
      # if your NebulaGraph server is in virtual network like k8s, please config the leader address of meta.
      meta:["127.0.0.1:9559"]
    }

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

    # Fill in the name of the graph space you want to write data to in the NebulaGraph.
    space: basketballplayer
    connection: {
      timeout: 3000
      retry: 3
    }
    execution: {
      retry: 3
    }
    error: {
      max: 32
      output: /tmp/errors
    }
    rate: {
      limit: 1024
      timeout: 1000
    }
  }
  # Processing vertices
  tags: [
    # Set the information about the Tag player.
    {
      # The corresponding Tag name in NebulaGraph.
      name: player
      type: {
        # Specify the data source file format to Pulsar.
        source: pulsar
        # Specify how to import the data into NebulaGraph. Only client is supported.
        sink: client
      }
      # The address of the Pulsar server.
      service: "pulsar://127.0.0.1:6650"
      # admin.url of pulsar.
      admin: "http://127.0.0.1:8081"
      # The Pulsar option can be configured from topic, topics or topicsPattern.
      options: {
        topics: "topic1,topic2"
      }

      # Specify the column names in the player table in fields, and their corresponding values are specified as properties in the NebulaGraph.
      # The sequence of fields and nebula.fields must correspond to each other.
      # If multiple column names need to be specified, separate them by commas.
      fields: [age,name]
      nebula.fields: [age,name]

      # Specify a column of data in the table as the source of VIDs in the NebulaGraph.
      vertex:{
          field:playerid
      # udf:{
      #            separator:"_"
      #            oldColNames:[field-0,field-1,field-2]
      #            newColName:new-field
      #        }
      # Add the specified prefix to the VID. For example, if the VID is `12345`, adding the prefix `tag1` will result in `tag1_12345`. The underscore cannot be modified.
      # prefix:"tag1"
      # Performs hashing operations on VIDs of type string.
      # policy:hash
      }

      # Batch operation types, including INSERT, UPDATE, and DELETE. defaults to INSERT.
      #writeMode: INSERT

      # Whether or not to delete the related incoming and outgoing edges of the vertices when performing a batch delete operation. This parameter takes effect when `writeMode` is `DELETE`.
      #deleteEdge: false

      # The number of data written to NebulaGraph in a single batch.
      batch: 10

      # The number of Spark partitions.
      partition: 10
      # The interval for message reading. Unit: second.
      interval.seconds: 10
    }
    # Set the information about the Tag Team.
    {
      name: team
      type: {
        source: pulsar
        sink: client
      }
      service: "pulsar://127.0.0.1:6650"
      admin: "http://127.0.0.1:8081"
      options: {
        topics: "topic1,topic2"
      }
      fields: [name]
      nebula.fields: [name]
      vertex:{
          field:teamid
      }
      batch: 10
      partition: 10
      interval.seconds: 10
    }

  ]

  # Processing edges
  edges: [
    # Set the information about Edge Type follow
    {
      # The corresponding Edge Type name in NebulaGraph.
      name: follow

      type: {
        # Specify the data source file format to Pulsar.
        source: pulsar

        # Specify how to import the Edge type data into NebulaGraph.
        # Specify how to import the data into NebulaGraph. Only client is supported.
        sink: client
      }

      # The address of the Pulsar server.
      service: "pulsar://127.0.0.1:6650"
      # admin.url of pulsar.
      admin: "http://127.0.0.1:8081"
      # The Pulsar option can be configured from topic, topics or topicsPattern.
      options: {
        topics: "topic1,topic2"
      }

      # Specify the column names in the follow table in fields, and their corresponding values are specified as properties in the NebulaGraph.
      # The sequence of fields and nebula.fields must correspond to each other.
      # If multiple column names need to be specified, separate them by commas.
      fields: [degree]
      nebula.fields: [degree]

      # In source, use a column in the follow table as the source of the edge's source vertex.
      # In target, use a column in the follow table as the source of the edge's destination vertex.
      source:{
          field:src_player
      # udf:{
      #            separator:"_"
      #            oldColNames:[field-0,field-1,field-2]
      #            newColName:new-field
      #        }
      # Add the specified prefix to the VID. For example, if the VID is `12345`, adding the prefix `tag1` will result in `tag1_12345`. The underscore cannot be modified.
      # prefix:"tag1"
      # Performs hashing operations on VIDs of type string.
      # policy:hash
      }

      target:{
          field:dst_player
      # udf:{
      #            separator:"_"
      #            oldColNames:[field-0,field-1,field-2]
      #            newColName:new-field
      #        }
      # Add the specified prefix to the VID. For example, if the VID is `12345`, adding the prefix `tag1` will result in `tag1_12345`. The underscore cannot be modified.
      # prefix:"tag1"
      # Performs hashing operations on VIDs of type string.
      # policy:hash
      }

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

      # Batch operation types, including INSERT, UPDATE, and DELETE. defaults to INSERT.
      #writeMode: INSERT

      # The number of data written to NebulaGraph in a single batch.
      batch: 10

      # The number of Spark partitions.
      partition: 10

      # The interval for message reading. Unit: second.
      interval.seconds: 10
    }

    # Set the information about the Edge Type serve
    {
      name: serve
      type: {
        source: Pulsar
        sink: client
      }
      service: "pulsar://127.0.0.1:6650"
      admin: "http://127.0.0.1:8081"
      options: {
        topics: "topic1,topic2"
      }

      fields: [start_year,end_year]
      nebula.fields: [start_year,end_year]
      source:{
          field:playerid
      }

      target:{
          field:teamid
      }

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

      batch: 10
      partition: 10
      interval.seconds: 10
    }
  ]
}

Step 3: Import data into NebulaGraph

Run the following command to import Pulsar data into NebulaGraph. For a description of the parameters, see Options for import.

${SPARK_HOME}/bin/spark-submit --master "local" --class com.vesoft.nebula.exchange.Exchange <nebula-exchange-3.5.0.jar_path> -c <pulsar_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-3.5.0.jar  -c /root/nebula-exchange/nebula-exchange/target/classes/pulsar_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 4: (optional) Validate data

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

LOOKUP ON player YIELD id(vertex);

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

Step 5: (optional) Rebuild indexes in NebulaGraph

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

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Last update: August 17, 2023