Node management
===============

All data nodes in a PGD cluster are members of one or more groups. By
default, all data nodes are members of the top-level group, which spans
all data nodes in the PGD cluster. Nodes can also belong to subgroups
that can be configured to reflect logical or geographical organization
of the PGD cluster.

You can manage nodes and groups using the various options available with
nodes and subgroups.

-  :ref:`Node types <Node types>`  covers the kinds of node that can exist in PGD
   clusters.

-  :ref:`Groups and subgroups <Groups and subgroups>`  goes into more detail on how groups and subgroups work
   in PGD

-  :ref:`Creating and joining groups <Creating and joining PGD groups>`  looks at how new PGD groups can be created and how to
   join PGD nodes to them.

-  :ref:`Witness nodes <Witness nodes>`  looks at 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 and how they
   are configured.

-  :ref:`Viewing topology <Viewing PGD topology>`  details commands and SQL queries that can show the
   structure of a PGD clusters nodes and groups.

-  :ref:`Removing nodes and groups <Removing nodes and groups>`  shows the process to follow to safely remove a node
   from a group or a group from a cluster.

-  :ref:`Heterogeneous clusters <Joining a heterogeneous cluster>`  looks at how your PGD cluster can interoperate with PGD
   nodes from earlier editions of PGD.

-  :ref:`Connection DSNs and SSL (TLS) <Connection DSNs and SSL (TLS)>`  introduces the DSNs or connection strings needed to
   connect directly to a node in a PGD cluster. It also covers how to
   use SSL/TLS certificates to provide authentication and encryption
   between servers and between clients.

-  :ref:`Decoding Worker <Decoding Worker>`  covers a feature of PGD that allows groups of nodes to
   reduce CPU overhead due to replication.

-  :ref:`Cleanup of replication slots <Cleanup of replication slots>`  examines how the Postgres replication slots are
   consumed when PGD is operating.

-  :ref:`Node restart and down node recovery <Node restart and down node recovery>`  details the steps needed to bring a node back into
   service after a failure or scheduled downtime and the impact it has
   on the cluster as it returns.

-  :ref:`Maintenance commands through proxies <Maintenance commands through proxies>`  shows how to send maintenance commands to nodes that
   you can’t directly access, such as those behind a proxy.

.. toctree::
  :maxdepth: 3

  Using--node_management--node_types
  Using--node_management--groups_and_subgroups
  Using--node_management--creating_and_joining
  Using--node_management--witness_nodes
  Using--node_management--logical_standby_nodes
  Using--node_management--subscriber_only
  Using--node_management--viewing_topology
  Using--node_management--removing_nodes_and_groups
  Using--node_management--heterogeneous_clusters
  Using--node_management--connections_dsns_and_ssl
  Using--node_management--decoding_worker
  Using--node_management--replication_slots
  Using--node_management--node_recovery
  Using--node_management--maintainance_with_proxies