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| author | Peter Eisentraut <peter@eisentraut.org> | 2023-03-20 08:48:46 +0100 |
|---|---|---|
| committer | Peter Eisentraut <peter@eisentraut.org> | 2023-03-20 08:48:46 +0100 |
| commit | 0b51d423e974557e821d890c0a3a49e419a19caa (patch) | |
| tree | c3bec8292067e791ab0a7bdeac143854ad50eba3 | |
| parent | 785f7095767e148995d276fe52f6b1e1af76e726 (diff) | |
| download | postgresql-0b51d423e974557e821d890c0a3a49e419a19caa.tar.gz postgresql-0b51d423e974557e821d890c0a3a49e419a19caa.zip | |
doc: Additional information about timeline ID hexadecimal format
Timeline IDs are sometimes presented to the user in hexadecimal format
(for example in WAL file names). Add a few bits of information to
clarify this.
Author: Sébastien Lardière <sebastien@lardiere.net>
Discussion: https://www.postgresql.org/message-id/flat/8fef346e-2541-76c3-d768-6536ae052993@lardiere.net
| -rw-r--r-- | doc/src/sgml/backup.sgml | 11 | ||||
| -rw-r--r-- | doc/src/sgml/config.sgml | 8 |
2 files changed, 18 insertions, 1 deletions
diff --git a/doc/src/sgml/backup.sgml b/doc/src/sgml/backup.sgml index be05a332050..8cb24d6ae54 100644 --- a/doc/src/sgml/backup.sgml +++ b/doc/src/sgml/backup.sgml @@ -1309,7 +1309,16 @@ restore_command = 'cp /mnt/server/archivedir/%f %p' a new timeline is created to identify the series of WAL records generated after that recovery. The timeline ID number is part of WAL segment file names so a new timeline does - not overwrite the WAL data generated by previous timelines. It is + not overwrite the WAL data generated by previous timelines. + For example, in the WAL file name + <filename>0000000100001234000055CD</filename>, the leading + <literal>00000001</literal> is the timeline ID in hexadecimal. (Note that + in other contexts, such as server log messages, timeline IDs are + usually printed in decimal.) + </para> + + <para> + It is in fact possible to archive many different timelines. While that might seem like a useless feature, it's often a lifesaver. Consider the situation where you aren't quite sure what point-in-time to recover to, diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index e5c41cc6c6d..481f93cea1b 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -4114,6 +4114,14 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows </para> <para> + To specify a timeline ID in hexadecimal (for example, if extracted + from a WAL file name or history file), prefix it with a + <literal>0x</literal>. For instance, if the WAL file name is + <filename>00000011000000A10000004F</filename>, then the timeline ID is + <literal>0x11</literal> (or 17 decimal). + </para> + + <para> You usually only need to set this parameter in complex re-recovery situations, where you need to return to a state that itself was reached after a point-in-time recovery. |