16 Developing Applications with Graph Analytics

In order to run graph algorithms, the graph application connects to the graph server (PGX) in the middle tier, which in turn connects to the Oracle Database.

• Using the Graph Server Administrator Dashboard
  The graph server administrator can efficiently track and manage the memory usage of the graph server (PGX) using the Administrator Dashboard.
• About Vertex and Edge IDs
  The graph server (PGX) enforces by default the existence of a unique identifier for each vertex and edge in a graph.
• Graph Management in the Graph Server (PGX)
  You can load a graph into the graph server (PGX) and perform different actions such as publish, store, or delete a graph.
• Keeping the Graph in Oracle Database Synchronized with the Graph Server
  You can use the FlashbackSynchronizer API to automatically apply changes made to graph in the database to the corresponding PgxGraph object in memory, thus keeping both synchronized.
• Optimizing Graphs for Read Versus Updates in the Graph Server (PGX)
  The graph server (PGX) can store an optimized graph for other reads or updates. This is only relevant when the updates are made directly to a graph instance in the graph server.
• Executing Built-in Algorithms
  The graph server (PGX) contains a set of built-in algorithms that are available as Java APIs.
• Using Custom PGX Graph Algorithms
  A custom PGX graph algorithm allows you to write a graph algorithm in Java syntax and have it automatically compiled to an efficient parallel implementation.
• Creating Subgraphs
  You can create subgraphs based on a graph that has been loaded into memory. You can use filter expressions or create bipartite subgraphs based on a vertex (node) collection that specifies the left set of the bipartite graph.
• User-Defined Functions (UDFs) in PGX
  User-defined functions (UDFs) allow users of PGX to add custom logic to their PGQL queries or custom graph algorithms, to complement built-in functions with custom requirements.
• Using Graph Server (PGX) as a Library
  When you utilize PGX as a library in your application, the graph server (PGX) instance runs in the same JVM as the Java application and all requests are translated into direct function calls instead of remote procedure invocations.