(fork)</glossterm>
   <glossdef>
    <para>
     A storage structure that keeps metadata about each data page of a table's
     main fork.  The free space map entry for each page stores the
     amount of free space that's available for future tuples, and is structured
     to be efficiently searched for available space for a new tuple of a given
     size.
    </para>
    <para>
     For more information, see
     <xref linkend="storage-fsm"/>.
    </para>
   </glossdef>
  </glossentry>

  <glossentry id="glossary-function">
   <glossterm>Function (routine)</glossterm>
   <glossdef>
    <para>
     A type of routine that receives zero or more arguments, returns zero or more
     output values, and is constrained to run within one transaction.
     Functions are invoked as part of a query, for example via
     <command>SELECT</command>.
     Certain functions can return
     <glossterm linkend="glossary-result-set">sets</glossterm>; those are
     called <firstterm>set-returning functions</firstterm>.
    </para>
    <para>
     Functions can also be used for
     <glossterm linkend="glossary-trigger">triggers</glossterm> to invoke.
    </para>
    <para>
     For more information, see
     <xref linkend="sql-createfunction"/>.
    </para>
   </glossdef>
  </glossentry>

  <glossentry>
   <glossterm>GMT</glossterm>
   <glosssee otherterm="glossary-utc" />
  </glossentry>

  <glossentry id="glossary-grant">
   <glossterm>Grant</glossterm>
   <glossdef>
    <para>
     An <acronym>SQL</acronym> command that is used to allow a
     <glossterm linkend="glossary-user">user</glossterm> or
     <glossterm linkend="glossary-role">role</glossterm> to access
     specific objects within the <glossterm linkend="glossary-database">database</glossterm>.
    </para>
    <para>
     For more information, see
     <xref linkend="sql-grant"/>.
    </para>
   </glossdef>
  </glossentry>

  <glossentry id="glossary-heap">
   <glossterm>Heap</glossterm>
   <glossdef>
    <para>
     Contains the values of <glossterm linkend="glossary-tuple">row</glossterm>
     attributes (i.e., the data) for a
     <glossterm linkend="glossary-relation">relation</glossterm>.
     The heap is realized within one or more
     <glossterm linkend="glossary-file-segment">file segments</glossterm>
     in the relation's <glossterm linkend="glossary-fork">main fork</glossterm>.
    </para>
   </glossdef>
  </glossentry>

  <glossentry id="glossary-host">
   <glossterm>Host</glossterm>
   <glossdef>
    <para>
     A computer that communicates with other computers over a network.
     This is sometimes used as a synonym for
     <glossterm linkend="glossary-server">server</glossterm>.
     It is also used to refer to a computer where
     <glossterm linkend="glossary-client">client processes</glossterm> run.
    </para>
   </glossdef>
  </glossentry>

  <glossentry id="glossary-index">
   <glossterm>Index (relation)</glossterm>
   <glossdef>
    <para>
     A <glossterm linkend="glossary-relation">relation</glossterm> that contains
     data derived from a <glossterm linkend="glossary-table">table</glossterm>
     or <glossterm linkend="glossary-materialized-view">materialized view</glossterm>.
     Its internal structure supports fast retrieval of and access to the original
     data.
    </para>
    <para>
     For more information, see
     <xref linkend="sql-createindex"/>.
    </para>
   </glossdef>
  </glossentry>
  <glossentry id="glossary-incremental-backup">
   <glossterm>Incremental backup</glossterm>
   <glossdef>
    <para>
     A special <glossterm linkend="glossary-basebackup">base backup</glossterm>
     that for some files may contain only those pages that were modified since
     a previous backup, as opposed to the full contents of every file. Like
     base backups, it is generated by the tool <xref linkend="app-pgbasebackup"/>.
    </para>
    <para>
     To restore incremental backups the tool <xref linkend="app-pgcombinebackup"/>
     is used, which