<productname>PostgreSQL</productname>,
     <firstterm>Class</firstterm> is an archaic synonym for
     <firstterm>relation</firstterm>.
    </para>
   </glossdef>
  </glossentry>

  <glossentry id="glossary-replica">
   <glossterm>Replica (server)</glossterm>
   <glossdef>
    <para>
     A <glossterm linkend="glossary-database">database</glossterm> that is paired
     with a <glossterm linkend="glossary-primary-server">primary</glossterm>
     database and is maintaining a copy of some or all of the primary database's
     data. The foremost reasons for doing this are to allow for greater access
     to that data, and to maintain availability of the data in the event that
     the <glossterm linkend="glossary-primary-server">primary</glossterm>
     becomes unavailable.
    </para>
   </glossdef>
  </glossentry>

  <glossentry id="glossary-replication">
   <glossterm>Replication</glossterm>
   <glossdef>
    <para>
     The act of reproducing data on one
     <glossterm linkend="glossary-server">server</glossterm> onto another
     server called a <glossterm linkend="glossary-replica">replica</glossterm>.
     This can take the form of <firstterm>physical replication</firstterm>,
     where all file changes from one server are copied verbatim,
     or <firstterm>logical replication</firstterm> where a defined subset
     of data changes are conveyed using a higher-level representation.
    </para>
   </glossdef>
  </glossentry>

  <glossentry id="glossary-restartpoint">
   <glossterm>Restartpoint</glossterm>
   <glossdef>
    <para>
     A variant of a <glossterm
     linkend="glossary-checkpoint">checkpoint</glossterm> performed on a
     <glossterm linkend="glossary-replica">replica</glossterm>.
    </para>
    <para>
     For more information, see <xref linkend="wal-configuration"/>.
    </para>
   </glossdef>
  </glossentry>

  <glossentry id="glossary-result-set">
   <glossterm>Result set</glossterm>
   <glossdef>
    <para>
     A <glossterm linkend="glossary-relation">relation</glossterm> transmitted
     from a <glossterm linkend="glossary-backend">backend process</glossterm>
     to a <glossterm linkend="glossary-client">client</glossterm> upon the
     completion of an <acronym>SQL</acronym> command, usually a
     <command>SELECT</command> but it can be an
     <command>INSERT</command>, <command>UPDATE</command>,
     <command>DELETE</command>, or <command>MERGE</command> command if the
     <literal>RETURNING</literal> clause is specified.
    </para>
    <para>
     The fact that a result set is a relation means that a query can be used
     in the definition of another query, becoming a
     <firstterm>subquery</firstterm>.
    </para>
   </glossdef>
   <glossdef>
    <para>
    </para>
   </glossdef>
  </glossentry>

  <glossentry id="glossary-revoke">
   <glossterm>Revoke</glossterm>
   <glossdef>
    <para>
     A command to prevent access to a named set of
     <glossterm linkend="glossary-database">database</glossterm> objects for a
     named list of <glossterm linkend="glossary-role">roles</glossterm>.
    </para>
    <para>
     For more information, see
     <xref linkend="sql-revoke"/>.
    </para>
   </glossdef>
  </glossentry>

  <glossentry id="glossary-role">
   <glossterm>Role</glossterm>
   <glossdef>
    <para>
     A collection of access privileges to the
     <glossterm linkend="glossary-database">instance</glossterm>.
     Roles are themselves a privilege that can be granted to other roles.
     This is often done for convenience or to ensure completeness
     when multiple <glossterm linkend="glossary-user">users</glossterm> need
     the same privileges.
    </para>
    <para>
     For more information, see
     <xref linkend="sql-createrole"/>.
    </para>
   </glossdef>
  </glossentry>

  <glossentry id="glossary-rollback">
   <glossterm>Rollback</glossterm>
   <glossdef>
    <para>
     A command to undo all of the operations performed since the beginning
     of a <glossterm linkend="glossary-transaction">transaction</glossterm>.