# Import data from JSON files¶

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

## Data set¶

This topic takes the basketballplayer dataset as an example. Some sample data are as follows:

• player

{"id":"player100","age":42,"name":"Tim Duncan"}
{"id":"player101","age":36,"name":"Tony Parker"}
{"id":"player102","age":33,"name":"LaMarcus Aldridge"}
{"id":"player103","age":32,"name":"Rudy Gay"}
...

• team

{"id":"team200","name":"Warriors"}
{"id":"team201","name":"Nuggets"}
...

• follow

{"src":"player100","dst":"player101","degree":95}
{"src":"player101","dst":"player102","degree":90}
...

• serve

{"src":"player100","dst":"team204","start_year":"1997","end_year":"2016"}
{"src":"player101","dst":"team204","start_year":"1999","end_year":"2018"}
...


## 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

## 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.
• Exchange has been compiled, or download the compiled .jar file directly.
• 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 properly.
• 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.
(partition_num = 10, \
replica_factor = 1, \
vid_type = FIXED_STRING(30));

## Use the graph space 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);


### Step 2: Process JSON files¶

Confirm the following information:

1. Process JSON files to meet Schema requirements.

2. Obtain the JSON file storage path.

### Step 3: Modify configuration files¶

After Exchange is compiled, copy the conf file target/classes/application.conf to set JSON data source configuration. In this example, the copied file is called json_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: {
# 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"]
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.
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 JSON.
source: json

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

# Specify the path to the JSON 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.json".
path: "hdfs://192.168.*.*:9000/data/vertex_player.json"

# Specify the key name in the JSON file in fields, and its corresponding value will serve as the data source for the properties specified in the Nebula Graph.
# If multiple column names need to be specified, separate them by commas.
fields: [age,name]

# 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 that in the JSON file.
# Currently, Nebula Graph 3.2.0 supports only strings or integers of VID.
vertex: {
field:id
}

# 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 JSON.
source: json

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

# Specify the path to the JSON 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.json".
path: "hdfs://192.168.*.*:9000/data/vertex_team.json"

# Specify the key name in the JSON file in fields, and its corresponding value will serve as the data source for the properties specified in the Nebula Graph.
# If multiple column names need to be specified, separate them by commas.
fields: [name]

# 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 vertex VID in the Nebula Graph.
# The value of vertex must be the same as that in the JSON file.
# Currently, Nebula Graph 3.2.0 supports only strings or integers of VID.
vertex: {
field:id
}

# 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 JSON.
source: json

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

# Specify the path to the JSON 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.json".
path: "hdfs://192.168.*.*:9000/data/edge_follow.json"

# Specify the key name in the JSON file in fields, and its corresponding value will serve as the data source for the properties specified in the Nebula Graph.
# If multiple column names need to be specified, separate them by commas.
fields: [degree]

# 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 that in the JSON file.
# Currently, Nebula Graph 3.2.0 supports only strings or integers of VID.
source: {
field: src
}
target: {
field: dst
}

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

# 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 JSON.
source: json

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

# Specify the path to the JSON 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.json".
path: "hdfs://192.168.*.*:9000/data/edge_serve.json"

# Specify the key name in the JSON file in fields, and its corresponding value will serve as the data source for the properties specified in the Nebula Graph.
# If multiple column names need to be specified, separate them by commas.
fields: [start_year,end_year]

# 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 that in the JSON file.
# Currently, Nebula Graph 3.2.0 supports only strings or integers of VID.
source: {
field: src
}
target: {
field: dst
}

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

# 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 JSON data into Nebula Graph. 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-3.0.0.jar_path> -c <json_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-echange/nebula-exchange/target/nebula-exchange-3.0.0.jar  -c /root/nebula-exchange/nebula-exchange/target/classes/json_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: August 12, 2022