Node types and capabilities

A PGD cluster can contain several different types of node, each with its own role. This section describes the different types of node that can be configured in a PGD cluster.

• :ref:`Overview of durability options <Overview of durability options>`  is an overview the kinds of node that can exist in PGD clusters and their associated roles.
  

• :ref:`Witness nodes <Witness nodes>`  looks at the witness node, a special class of PGD node, dedicated to establishing consensus in a group.
  

• :ref:`Logical standby nodes <Logical standby nodes>`  shows how to efficiently keep a node on standby synchronized and ready to step in as a primary in the case of failure.
  

• :ref:`Subscriber-only nodes and groups <Subscriber-only nodes and groups>`  looks at how subscriber-only nodes work with subscriber-only groups, how they boost read scalability and the different options for configuring them.
  

• An overview of PGD Node types
  • Data nodes
  • Witness nodes
  • Logical standby nodes
  • Subscriber-only nodes
• Witness nodes
  • Witness nodes within PGD groups or regions
  • Witness node outside regions
• Logical standby nodes
• Subscriber-only nodes and groups
  • An overview of Subscriber-only nodes
    • Overview
    • Subscriber-only nodes
    • Subscriber-only groups
    • Optimizing subscriber-only groups
    • Subscriber-only nodes and DDL
  • Creating Subscriber-only groups and nodes
    • Creating a Subscriber-only group manually
    • Adding a node to a new Subscriber-only group manually
  • Joining nodes to a Subscriber-only group
    • Joining a node to an existing subscriber-only group
  • Optimizing subscriber-only groups
    • Requirements for the optimized topology
    • How the optimized topology works
    • Subscriber-only group leaders
    • Group leaders in the optimized topology
    • Enabling the optimized model