.backup files not needed?

Just had questions from a replication user about why the .backup file is
described as "can ordinarily be ignored" and is considered optional by
recovery also even when pg_start_backup() was used.

If the file was created, it is necessary to use it in recovery, so
should never be ignored as the docs imply.

Can we remove the phrase ", and can ordinarily be ignored." ? from
doc/src/sgml/backup.sgml

  <para>
    To make use of the backup, you will need to keep around all the WAL
    segment files generated during and after the file system backup.
    To aid you in doing this, the <function>pg_stop_backup</> function
    creates a <firstterm>backup history file</> that is immediately
    stored into the WAL archive area. This file is named after the first
    WAL segment file that you need to have to make use of the backup.
    For example, if the starting WAL file is
    <literal>0000000100001234000055CD</> the backup history file will be
    named something like
    <literal>0000000100001234000055CD.007C9330.backup</>. (The second
    part of the file name stands for an exact position within the WAL
    file, and can ordinarily be ignored.) Once you have safely archived
    the file system backup and the WAL segment files used during the
    backup (as specified in the backup history file), all archived WAL
    segments with names numerically less are no longer needed to recover
    the file system backup and can be deleted. However, you should
    consider keeping several backup sets to be absolutely certain that
    you can recover your data.
   </para>

--
  Simon Riggs
  2ndQuadrant  http://www.2ndQuadrant.com