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neo4j-to-neptune

A command-line utility for migrating data from Neo4j to Neptune.

Examples

java -jar neo4j-to-neptune.jar convert-csv -i /tmp/neo4j-export.csv -d output --infer-types

Build

mvn clean install

Usage

Migration Process

Migration of data from Neo4j to Neptune is a multi-step process:

  1. Export CSV from Neo4j – Use the APOC export procedures to export data from Neptune to CSV.
  2. Convert CSV – Use the convert-csv command-line utility to convert the exported CSV into the Neptune Gremlin bulk load CSV format.
  3. Bulk Load into Neptune – Use the Neptune bulk load API to load data into Neptune.

Export CSV from Neo4j

Use the apoc.export.csv.all procedure from neo4j's APOC library to export data from Neo4j to CSV.

1. Install APOC

Follow the instructions for installing the APOC library for either Neo4j Desktop or Neo4j Server.

2. Enable exports

Update the neo4j.conf configuration file to enable exports:

apoc.export.file.enabled=true

3. Export to CSV

CALL apoc.export.csv.all(
 "neo4j-export.csv", 
 {d:','}
)

The path that you specify for the export file will be resolved relative to the Neo4j import directory. apoc.export.csv.all creates a single CSV file containing data for all nodes and relationships.

Convert CSV

Use the convert-csv command-line utility to convert the CSV exported from Neo4j into the Neptune Gremlin bulk load CSV format.

The utility has two required parameters: the path to the Neo4j export file and the name of a directory where the converted CSV files will be written. There are also optional parameters that allow you to specify node and relationship multi-valued property policies and turn on data type inferencing.

Multi-valued property policies

Neo4j allows 'homogeneous lists of simple types' to be stored as properties on both nodes and edges. These lists can contain duplicate values.

Neptune provides for set and single cardinality for vertex properties, and single cardinality for edge properties. Hence, there is no straightforward migration of Neo4j node list properties containing duplicate values into Neptune vertex properties, or Neo4j relationship list properties into Neptune edge properties.

The --node-property-policy and --relationship-property-policy parameters allow you to control the migration of multi-valued properties into Neptune.

--node-property-policy takes one of four values, the default being PutInSetIgnoringDuplicates:

  • LeaveAsString – Store a multi-valued Neo4j node property as a string representation of a JSON-formatted list
  • Halt – Halt (throw an exception) if a multi-valued Neo4j node property is encountered
  • PutInSetIgnoringDuplicates – Convert a multi-valued Neo4j node property to a set cardinality Neptune property, discarding duplicate values
  • PutInSetButHaltIfDuplicates – Convert a multi-valued Neo4j node property to a set cardinality Neptune property, discarding duplicate values but halt (throw an exception) if a multi-valued Neo4j node property containing duplicate values is encountered

--relationship-property-policy takes one of two values, the default being LeaveAsString:

  • LeaveAsString – Store a multi-valued Neo4j relationship property as a string representation of a JSON-formatted list
  • Halt – Halt (throw an exception) if a multi-valued Neo4j relationship property is encountered

Data type inferencing

When importing data into Neptune using the bulk loader, you can specify the data type for each property. If you supply an --infer-types flag to convert-csv, the utility will attempt to infer the narrowest supported type for each column in the output CSV.

Note that convert-csv will always use a double for values with decimal or scientific notation.

Bulk Load into Neptune

Use the Neptune bulk loader to load data into Neptune from the converted CSV files.