Durability Terminology
======================

.. _durability-terminology-1:

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

This page covers terms and definitions directly related to PGD’s
durability options. For other terms, see the main :ref:`Terminology <Terminology>`  section.

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.