<glossterm>Logger (process)</glossterm>
   <glossdef>
    <para>
     An <glossterm linkend="glossary-auxiliary-proc">auxiliary process</glossterm>
     which, if enabled, writes information about database events into the current
     <glossterm linkend="glossary-log-file">log file</glossterm>.
     When reaching certain time- or
     volume-dependent criteria, a new log file is created.
     Also called <firstterm>syslogger</firstterm>.
    </para>
    <para>
     For more information, see
     <xref linkend="runtime-config-logging"/>.
    </para>
   </glossdef>
  </glossentry>

  <glossentry id="glossary-logical-replication-cluster">
   <glossterm>Logical replication cluster</glossterm>
   <glossdef>
    <para>
     A set of publisher and subscriber instances with the publisher instance
     replicating changes to the subscriber instance.
    </para>
   </glossdef>
  </glossentry>

  <glossentry id="glossary-log-record">
   <glossterm>Log record</glossterm>
    <glossdef>
     <para>
      Archaic term for a <glossterm linkend="glossary-wal-record">WAL record</glossterm>.
     </para>
    </glossdef>
  </glossentry>

  <glossentry id="glossary-log-sequence-number">
   <glossterm>Log sequence number</glossterm>
   <acronym>LSN</acronym>
   <glossdef>
    <para>
     Byte offset into the <glossterm linkend="glossary-wal">WAL</glossterm>,
     increasing monotonically with each new <glossterm
     linkend="glossary-wal-record">WAL record</glossterm>.
    </para>
    <para>
     For more information, see <link
     linkend="datatype-pg-lsn"><type>pg_lsn</type></link> and <xref
     linkend="wal-internals"/>.
    </para>
   </glossdef>
  </glossentry>

  <glossentry>
   <glossterm>LSN</glossterm>
   <glosssee otherterm="glossary-log-sequence-number"/>
  </glossentry>

  <glossentry>
   <glossterm>Master (server)</glossterm>
   <glosssee otherterm="glossary-primary-server" />
  </glossentry>

  <glossentry id="glossary-materialized">
   <glossterm>Materialized</glossterm>
   <glossdef>
    <para>
     The property that some information has been pre-computed and stored
     for later use, rather than computing it on-the-fly.
    </para>
    <para>
     This term is used in
     <glossterm linkend="glossary-materialized-view">materialized view</glossterm>,
     to mean that the data derived from the view's query is stored on
     disk separately from the sources of that data.
    </para>
    <para>
     This term is also used to refer to some multi-step queries to mean that
     the data resulting from executing a given step is stored in memory
     (with the possibility of spilling to disk), so that it can be read multiple
     times by another step.
    </para>
   </glossdef>
  </glossentry>

  <glossentry id="glossary-materialized-view">
   <glossterm>Materialized view (relation)</glossterm>
   <glossdef>
    <para>
     A <glossterm linkend="glossary-relation">relation</glossterm> that is
     defined by a <command>SELECT</command> statement
     (just like a <glossterm linkend="glossary-view">view</glossterm>),
     but stores data in the same way that a
     <glossterm linkend="glossary-table">table</glossterm> does. It cannot be
     modified via <command>INSERT</command>, <command>UPDATE</command>,
     <command>DELETE</command>, or <command>MERGE</command> operations.
    </para>
    <para>
     For more information, see
     <xref linkend="sql-creatematerializedview"/>.
    </para>
   </glossdef>
  </glossentry>

  <glossentry id="glossary-merge">
   <glossterm>Merge</glossterm>
   <glossdef>
    <para>
     An <acronym>SQL</acronym> command used to conditionally add, modify,
     or remove <glossterm linkend="glossary-tuple">rows</glossterm>
     in a given <glossterm linkend="glossary-table">table</glossterm>,
     using data from a source
     <glossterm linkend="glossary-relation">relation</glossterm>.
    </para>
    <para>
     For more information, see
     <xref linkend="sql-merge"/>.
    </para>
   </glossdef>
  </glossentry>