Durability terminology
======================

.. _durability-terminology-1:

Durability terminology
----------------------

This page covers terms and definitions directly related to PGD’s
durability options. For other terms, see :ref:`Postgres Distributed terminology <Postgres Distributed terminology>`  .

Nodes
^^^^^

PGD nodes take different roles during the replication of a transaction.
These are implicitly assigned per transaction and are unrelated even for
concurrent transactions.

- The *origin* is the node that receives the transaction from the client
  or application. It’s the node processing the transaction first,
  initiating replication to other PGD nodes and responding back to the
  client with a confirmation or an error.

- The *origin node group* is a PGD group which includes the origin.

- A *partner* node is a PGD node expected to confirm transactions
  according to Group Commit requirements.

- A *commit group* is the group of all PGD nodes involved in the commit,
  that is, the origin and all of its partner nodes, which can be just a
  few or all peer nodes.