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<chapter id="backup">
<title>Backup and Restore</title>
<para>
To make use of this backup, you will need to keep around all the WAL
- segment files generated at or after the starting time of the backup.
+ 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
- this file name stands for an exact position within the WAL file, and can
- ordinarily be ignored.) Once you have safely archived this WAL
- segment file, you can delete all archived WAL segments with names numerically
- preceding this one. The backup history file is just a small text file.
- It contains the label string you gave to <function>pg_start_backup</>, as
- well as the starting and ending times of the backup. If you used the
- label to identify where the associated dump file is kept, then the
- archived history file is enough to tell you which dump file to restore,
- should you need to do so.
+ 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
+ number in the file name stands for an exact position within the WAL
+ file, and can ordinarily be ignored.) Once you have safely archived
+ the WAL segment files used during the file system backup (as
+ specified in the backup history file), you can delete all archived
+ WAL segments with names numerically less. Keep in mind that only
+ completed WAL segment files are archived, so there will be delay
+ between running <function>pg_stop_backup</> and the archiving of
+ all WAL segment files needed to make the file system backup
+ consistent.
+ </para>
+ <para>
+ The backup history file is just a small text file. It contains the
+ label string you gave to <function>pg_start_backup</>, as well as
+ the starting and ending times of the backup. If you used the label
+ to identify where the associated dump file is kept, then the
+ archived history file is enough to tell you which dump file to
+ restore, should you need to do so.
</para>
<para>