MySQL data

You can use the Dgraph migration tool to convert a MySQL database tables into a schema and RDF file, and then load the resulting dataset into Dgraph.

Deriving a Dgraph schema from SQL

Before converting the data, the migration tool needs to derive the schema of each predicate. Dgraph follows two simple rules for converting the schema:

1. For plain attributes, there is usually a one-to-one mapping between a SQL data type and the Dgraph datatype. For instance, a Body column in the Posts table is of type text, and hence, the predicate posts.Body is of type string: posts.Body: string .
2. The predicates representing inter-object relationships, like posts.OwnerUserId., simply have the type [uid], meaning following the predicate leads us to a set of other objects.

Using the Migration tool

You can run the Dgraph migrate tool using this command:

dgraph migrate [flags]

1. Create a config.properties file that has the following settings and values should not be in quotes:

   user = <SQL_DB_USERNAME>
   password = <SQL_DB_PASSWORD>
   db = <SQL_DB>

2. Export the SQL database into schema.txt and sql.rdf file:

   dgraph migrate --config config.properties --output_schema schema.txt --output_data sql.rdf

   An output similar to this appears:

   Dumping table xyz
   Dumping table constraints xyz
   ...

note

If you are connecting to a remote DB hosted on AWS, GCP, and others, you need to pass the flags --host, and --port. For description of the various flags in the migration tool, see command line options.

After the migration is complete, two new files are available:

• an RDF file sql.rdf containing all the N-Quad entries
• a schema file schema.txt.

Importing the data

The two files can then be imported into Dgraph using the Dgraph Live Loader or Bulk Loader. Sometimes you might want to customize your schema. For example, you might add an index to a predicate, or change an inter-object predicate (edge) from unidirectional to bidirectional by adding the @reverse directive. If you would like such customizations, you should do it by editing the schema file generated by the migration tool before feeding the files to the Live Loader or Bulk Loader.

• To import the data into Dgraph using the Live Loader to Dgraph Zero and Alpha servers running on the default ports use:

  dgraph live -z localhost:5080 -a localhost:9080 --files sql.rdf --format=rdf --schema schema.txt

• To import data to Dgraph Cloud use:

   dgraph live --slash_grpc_endpoint=<grpc-endpoint>:443 -f sql.rdf --format=rdf --schema schema.txt -t <api-token>

  For detailed instructions to import data to Dgraph cloud, see import data.