The UPDATE queries make changes to existing graphs using the INSERT, UPDATE, and DELETE operations as detailed in the section Graph Modification of the PGQL 1.3 specification.

Note that INSERT allows you to insert new vertices and edges into a graph, UPDATE allows you to update existing vertices and edges by setting their properties to new values, and DELETE allows you to delete vertices and edges from a graph.

• Updatability of Graphs Through PGQL
  Graph data that is loaded from the Oracle RDBMS or from CSV files into the PGX is not updatable through PGQL right away.
• Executing UPDATE Queries against a Graph in the in-memory Graph Server (PGX)
  To execute UPDATE queries against a graph, use the PgxGraph.executePgql(String query) method.
• Executing UPDATE Queries Against a PGX Session
  For now, there is no support for executing UPDATE queries against a PgxSession and therefore, updates always have to be executed against a PgxGraph. To obtain a graph from a session, use the PgxSession.getGraph(String graphName) method.
• Altering the Underlying Schema of a Graph
  The INSERT operations can only insert vertices and edges with known labels and properties. Similarly, UPDATE operations can only set values of known properties. Thus, new data must always conform to the existing schema of the graph.