1. Graph Developer's Guide for Property Graph
  2. SQL Property Graphs
  3. Loading a SQL Property Graph into the Graph Server (PGX)
  4. Loading a SQL Property Graph Using the readGraphByName API

6.1 Loading a SQL Property Graph Using the readGraphByName API

You can load a SQL property graph into the graph server (PGX) by calling the readGraphByName API on a PgxSession object.

When loading a SQL property graph into the graph server (PGX), the full graph schema will be determined and mapped to a graph configuration. The graphs will be loaded as partitioned graphs where each vertex or edge table will be mapped to the respective vertex or edge provider of the same name. Labels and properties will also be loaded as defined.

However, note that only one label per vertex or edge table is supported in order to load a SQL graph into the graph server (PGX).

For example, consider the following SQL property graph:

CREATE PROPERTY GRAPH student_network
  VERTEX TABLES (
    persons KEY (person_id)
      LABEL person
        PROPERTIES (person_id, name, birthdate AS dob)
  )
  EDGE TABLES (
    friendships AS friends
      KEY (friendship_id)
      SOURCE KEY (person_a) REFERENCES persons(person_id)
      DESTINATION KEY (person_b) REFERENCES persons(person_id)
      PROPERTIES (friendship_id, meeting_date)
  );

You can load this SQL graph into memory as shown:

opg4j> var graph = session.readGraphByName ("STUDENT_NETWORK",GraphSource.PG_SQL)
graph ==> PgxGraph[name=STUDENTS_NETWORK,N=4,E=4,created=1681007796946]
PgxGraph graph = session.readGraphByName("STUDENT_NETWORK", GraphSource.PG_SQL);
>>> graph = session.read_graph_by_name("STUDENT_NETWORK", "pg_sql")
>>> graph
PgxGraph(name: STUDENTS_NETWORK, v: 4, e: 4, directed: True, memory(Mb): 0)

Parent topic: Loading a SQL Property Graph into the Graph Server (PGX)

6.1.1 Loading a SQL Property Graph from a Different Schema

You can specify the schema name when using the readGraphByName API for loading a SQL property graph.

If you only provide the graph name when calling the readGraphByName API, it is assumed that the graph is owned by current user. But if you want to load a graph owned by another user, then you must provide the schema name as well. Also, ensure that you have SELECT permission on the SQL graph and all its underlying data tables.

The following example loads a SQL property graph from the GRAPHUSER schema: 

opg4j> var graph = session.readGraphByName("GRAPHUSER", "STUDENT_NETWORK", GraphSource.PG_SQL)
graph ==> PgxGraph[name=STUDENT_NETWORK,N=4,E=4,created=1680769031393]

PgxGraph graph = session.readGraphByName("GRAPHUSER", "STUDENT_NETWORK", GraphSource.PG_SQL);
>>> graph = session.read_graph_by_name("STUDENT_NETWORK", "pg_sql", "GRAPHUSER")
>>> graph
PgxGraph(name: STUDENT_NETWORK_2, v: 4, e: 4, directed: True, memory(Mb): 0)

See Also:

Privileges to Load a SQL Property Graph

Parent topic: Loading a SQL Property Graph Using the readGraphByName API

6.1.2 Loading a SQL Property Graph Using Graph Optimization Options

You can optimize the read or update performance, when loading a SQL property graph using the graph optimization options.

The following example shows loading a SQL property graph optimized for READ operation: 

opg4j> var graph = session.readGraphByName("STUDENT_NETWORK", GraphSource.PG_SQL,
...>     ReadGraphOption.optimizeFor(GraphOptimizedFor.READ))
graph ==> PgxGraph[name=STUDENT_NETWORK,N=4,E=4,created=1681008951415]
PgxGraph graph = session.readGraphByName("STUDENT_NETWORK", GraphSource.PG_SQL,
  ReadGraphOption.optimizeFor(GraphOptimizedFor.READ);
>>> session.read_graph_by_name('STUDENT_NETWORK', 'pg_sql', options=['optimized_for_read'])
PgxGraph(name: STUDENT_NETWORK, v: 4, e: 4, directed: True, memory(Mb): 0)

The following example shows loading a SQL property graph optimized for UPDATE operation. Also, note that the READ and UPDATE options cannot be used at the same time. 

opg4j> var graph = session.readGraphByName("STUDENT_NETWORK", GraphSource.PG_SQL,
...>     ReadGraphOption.optimizeFor(GraphOptimizedFor.UPDATES))
graph ==> PgxGraph[name=STUDENT_NETWORK_2,N=4,E=4,created=1681009073501]
PgxGraph graph = session.readGraphByName("STUDENT_NETWORK", GraphSource.PG_SQL,
  ReadGraphOption.optimizeFor(GraphOptimizedFor.UPDATES));
>>> session.read_graph_by_name('STUDENT_NETWORK', 'pg_sql', options=['optimized_for_updates'])
PgxGraph(name: STUDENT_NETWORK, v: 4, e: 4, directed: True, memory(Mb): 0)

The following example shows loading a SQL property graph with the SYNCHRONIZABLE optimization option. This option can be used in combination with the READ and UPDATE options. 

opg4j> var graph = session.readGraphByName("STUDENT_NETWORK", GraphSource.PG_SQL,
...>                            ReadGraphOption.SYNCHRONIZABLE)
graph ==> PgxGraph[name=STUDENT_NETWORK,N=4,E=4,created=1696341305374]
PgxGraph graph = session.readGraphByName("STUDENT_NETWORK", GraphSource.PG_SQL,
  ReadGraphOption.SYNCHRONIZABLE);
>>> session.read_graph_by_name('STUDENT_NETWORK', 'pg_sql', options=['synchronizable'])
PgxGraph(name: STUDENT_NETWORK_2, v: 4, e: 4, directed: True, memory(Mb): 0)

Parent topic: Loading a SQL Property Graph Using the readGraphByName API

6.1.3 Loading a SQL Property Graph Using OnMissingVertex Options

If either the source or destination vertex or both are missing for an edge, then you can use the OnMissingVertexOption to specify the behavior for handling the edge with the missing vertex.

The supported values are:
  • OnMissingVertex.ERROR (default): Specifies that an error must be thrown for edges with missing source or destination vertex.
  • OnMissingVertex.IGNORE_EDGE: Specifies that the edge for a missing source or destination vertex must be ignored.
  • OnMissingVertex.IGNORE_EDGE_LOG: Specifies that the edge for a missing source or destination vertex must be ignored and all ignored edges must be logged.
  • OnMissingVertex.IGNORE_EDGE_LOG_ONCE: Specifies that the edge for a missing source or destination vertex must be ignored and only the first ignored edge must be logged.

The following example loads a SQL property graph by ignoring the edges with missing vertices and logging only the first ignored edge.

opg4j> session.readGraphByName("STUDENT_NETWORK", GraphSource.PG_SQL,
...>      ReadGraphOption.onMissingVertex(OnMissingVertex.IGNORE_EDGE_LOG_ONCE))
$2 ==> PgxGraph[name=STUDENT_NETWORK_2,N=4,E=4,created=1697264084059]
PgxGraph graph = session.readGraphByName("STUDENT_NETWORK", GraphSource.PG_SQL,
  ReadGraphOption.onMissingVertex(OnMissingVertex.IGNORE_EDGE_LOG_ONCE));
>>> session.read_graph_by_name('STUDENT_NETWORK', 'pg_sql',
    options=['on_missing_vertex_ignore_edge_log_once'])
PgxGraph(name: STUDENT_NETWORK, v: 4, e: 4, directed: True, memory(Mb): 0)

Parent topic: Loading a SQL Property Graph Using the readGraphByName API