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Update PITR mention of which WAL files are needed.

This commit is contained in:
Bruce Momjian 2005-04-18 01:29:00 +00:00
parent db30652135
commit d755688f24
1 changed files with 26 additions and 17 deletions
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43
doc/src/sgml/backup.sgml
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@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/backup.sgml,v 2.61 2005/04/17 03:05:19 momjian Exp $
$PostgreSQL: pgsql/doc/src/sgml/backup.sgml,v 2.62 2005/04/18 01:29:00 momjian Exp $
-->
<chapter id="backup">
<title>Backup and Restore</title>
@ -724,23 +724,32 @@ SELECT pg_stop_backup();
<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>