How to perform PostgreSQL point-in-time recovery

「爱情、让人受尽委屈。」 2023-10-18 22:14 135阅读 0赞

### How to perform PostgreSQL point-in-time recovery ###

by Milosz Galazka on February 29, 2016 and tagged with [Debian][], [Jessie][], [PostgreSQL][]

This blog post is an update to the earlier PostgreSQL entries in which I will show you how to use continuous **Write Ahead Log** archiving to take advantage of the point-in-time recovery.

#### Table of contents ####

*  [Initial notes][]
 *  [Database configuration][]
 *  [Create initial database backup][]
 *  [Recovery process - restore to the most recent state][]
 *  [Recovery process - restore to the specific point in time][]
 *  [Recovery process - restore to the named restore point][]
 *  [Recovery process - restore to the specific point in time using hot standby mode][]
 *  [Additional notes][]
 *  [References][]

#### Initial notes ####

I will use *Debian Jessie* and *PostgreSQL 9.4* database server.

debian:~$ lsb_release -a
    No LSB modules are available.
    Distributor ID: Debian
    Description:    Debian GNU/Linux 8.2 (jessie)
    Release:        8.2
    Codename:       jessie

postgres@debian:~$ psql -A -t -c "select version()"
    PostgreSQL 9.4.5 on x86_64-unknown-linux-gnu, compiled by gcc (Debian 4.9.2-10) 4.9.2, 64-bit

#### Database configuration ####

Create `archive/wal`, `archive/base`, `archive/repo` and `archive/temp` directories inside `postgres` home directory.

debian:~$ sudo su - postgres

postgres@debian:~$ mkdir -p archive/{wal,base,repo,temp}

Set proper permissions on the created directories.

postgres@debian:~$ chmod -R 0700 archive

`archive/wal` directory will be used to store **Write Ahead Log** file segments continuously, `archive/base` will contain basic database backup, `archive/repo` will serve as an old backup repository, `archive/temp` will be used only temporarily.

Specify logging information required for **Write Ahead Log** archiving.

debian:~$ sudo sed -i -e "s/^#wal_level = minimal/wal_level = archive/" /etc/postgresql/9.4/main/postgresql.conf

Enable archive mode on database server.

debian:~$ sudo sed -i -e "s/^#archive_mode = off/archive_mode = on/" /etc/postgresql/9.4/main/postgresql.conf

Define shell command that will be used to store each completed **Write Ahead Log** file segment.

debian:~$ sudo sed -i -e "s/^#archive_command = ''/archive_command = 'test ! -f \/var\/lib\/postgresql\/archive\/wal\/%f.xz \&\& xz < %p > \/var\/lib\/postgresql\/archive\/wal\/%f.xz'/" /etc/postgresql/9.4/main/postgresql.conf

`%f` parameter will be expanded to file name, `%p` parameter will be expanded to path name relative to the cluster data directory.

Restart PostgreSQL service to apply changes.

postgres@debian:~$ pg_ctlcluster 9.4 main restart

#### Create initial database backup ####

I will use standard file system utilities instead of `pg_basebackup` as this utility is available since *PostgreSQL 9.1* and not before that. Repeat this procedure every week or month to keep backups off-line and speed up recovery process. You can use [rsync][] to keep backups on different servers.

Backup currently archived **Write Ahead Log** file segments to clean the `archive/wal` directory.

postgres@debian:~$ mv /var/lib/postgresql/archive/wal/* /var/lib/postgresql/archive/temp/

postgres@debian:~$ tar --remove-files -cf /var/lib/postgresql/archive/repo/wal_$(hostname)_$(date +%Y-%m-%d_%H%M).tar /var/lib/postgresql/archive/temp/*

Backup currently archived `base` directory to clean the `archive/base` directory.

postgres@debian:~$ tar --remove-files -cfJ /var/lib/postgresql/archive/repo/base_$(hostname)_$(date +%Y-%m-%d_%H%M).txz /var/lib/postgresql/archive/base/*

Create checkpoint in the database and write backup label file to start backup mode.

postgres@debian:~$ psql -A -t -c "select pg_start_backup('Backup created $(date +%d/%m/%Y\ %H:%M) at $(hostname)')"
    0/5C000028

Copy database to defined earlier `archive/base` location.

postgres@debian:~$ cp -pr /var/lib/postgresql/9.4/main/* /var/lib/postgresql/archive/base/

Stop backup mode and perform automatic switch to the next `Write Ahead Log` segment.

postgres@debian:~$ psql  -A -t -c "select pg_stop_backup()"
    NOTICE:  pg_stop_backup complete, all required WAL segments have been archived
    0/60003E20

Remove obsolete `postmaster.opts` and `postmaster.pid` files **from backup**.

postgres@debian:~$ rm /var/lib/postgresql/archive/base/postmaster.*

Remove **Write Ahead Log** file segments **stored inside base backup** as these files are very likely outdated and we have already gathered current files inside `archive/wal` directory.

postgres@debian:~$ rm -r /var/lib/postgresql/archive/base/pg_xlog/*

Now you have complete backup inside `/var/lib/postgresql/archive/base/` directory and current **Write Ahead Log** compressed file segments inside `/var/lib/postgresql/archive/wal/` directory.

#### Recovery process - restore to the most recent state ####

Stop database server.

postgres@debian:~$ pg_ctlcluster 9.4 main stop

Backup current database files.

postgres@debian:~$ mv /var/lib/postgresql/9.4/main /var/lib/postgresql/9.4/main.before_recovery

Copy archived database files.

postgres@debian:~$ cp -rp /var/lib/postgresql/archive/base /var/lib/postgresql/9.4/main

Create simple recovery file to restore every available **Write Ahead Log** file segment.

This solution introduces `recovery.conf` recovery configuration file as **Write Ahead Log** file segments are compressed and stored in different location.

Start the database server to perform recovery.

postgres@debian:~$ pg_ctlcluster 9.4 main start

Monitor recovery process.

postgres@debian:~$ tail /var/log/postgresql/postgresql-9.4-main.log

2016-01-22 16:35:56 CET [6622-1] LOG:  database system was interrupted; last known up at 2016-01-22 16:13:48 CET
    2016-01-22 16:35:56 CET [6622-2] LOG:  starting archive recovery
    2016-01-22 16:35:56 CET [6622-3] LOG:  restored log file "00000001000000000000005C" from archive
    2016-01-22 16:35:56 CET [6622-4] LOG:  redo starts at 0/5C000090
    2016-01-22 16:35:56 CET [6622-5] LOG:  restored log file "00000001000000000000005D" from archive
    2016-01-22 16:35:56 CET [6622-6] LOG:  restored log file "00000001000000000000005E" from archive
    2016-01-22 16:35:57 CET [6622-7] LOG:  restored log file "00000001000000000000005F" from archive
    2016-01-22 16:35:57 CET [6622-8] LOG:  restored log file "000000010000000000000060" from archive
    2016-01-22 16:35:57 CET [6622-9] LOG:  consistent recovery state reached at 0/60003E20
    2016-01-22 16:35:57 CET [6622-10] LOG:  restored log file "000000010000000000000061" from archive
    2016-01-22 16:35:57 CET [6622-11] LOG:  restored log file "000000010000000000000062" from archive
    2016-01-22 16:35:58 CET [6622-12] LOG:  restored log file "000000010000000000000063" from archive
    2016-01-22 16:35:58 CET [6622-13] LOG:  restored log file "000000010000000000000064" from archive
    sh: 1: cannot open /var/lib/postgresql/archive/wal/000000010000000000000065.xz: No such file
    2016-01-22 16:35:58 CET [6622-14] LOG:  redo done at 0/64003E78
    2016-01-22 16:35:58 CET [6622-15] LOG:  last completed transaction was at log time 2016-01-22 16:22:20.237615+01
    2016-01-22 16:35:59 CET [6622-16] LOG:  restored log file "000000010000000000000064" from archive
    sh: 1: cannot open /var/lib/postgresql/archive/wal/00000002.history.xz: No such file
    2016-01-22 16:35:59 CET [6622-17] LOG:  selected new timeline ID: 2
    sh: 1: cannot open /var/lib/postgresql/archive/wal/00000001.history.xz: No such file
    2016-01-22 16:36:00 CET [6622-18] LOG:  archive recovery complete
    2016-01-22 16:36:01 CET [6622-19] LOG:  MultiXact member wraparound protections are now enabled

#### Recovery process - restore to the specific point in time ####

Stop database server.

postgres@debian:~$ pg_ctlcluster 9.4 main stop

Backup current database files.

postgres@debian:~$ mv /var/lib/postgresql/9.4/main /var/lib/postgresql/9.4/main.before_recovery

Copy archived database files.

postgres@debian:~$ cp -rp /var/lib/postgresql/archive/base /var/lib/postgresql/9.4/main

Create recovery file to restore database to the point in time specified by `recovery_target_time` directive.

postgres@debian:~$ cat << EOF | tee /var/lib/postgresql/9.4/main/recovery.conf
    # provide missing wal file segments
    restore_command = 'xz --decompress < /var/lib/postgresql/archive/wal/%f.xz > %p'
    
    # recovery target time
    recovery_target_time='2016-01-22 23:05:10'
    
    # end recovery after reaching target time
    pause_at_recovery_target=false        # 9.4
    # recovery_target_action=promote      # 9.5
    
    # apply commits older than target time
    recovery_target_inclusive = false
    EOF

Start the database server to perform recovery.

postgres@debian:~$ pg_ctlcluster 9.4 main start

Monitor recovery process.

postgres@debian:~$ tail /var/log/postgresql/postgresql-9.4-main.log

2016-01-22 23:06:55 CET [8062-1] LOG:  database system was interrupted; last known up at 2016-01-22 23:03:42 CET
    2016-01-22 23:06:55 CET [8062-2] LOG:  starting point-in-time recovery to 2016-01-22 23:05:10+01
    2016-01-22 23:06:55 CET [8062-3] LOG:  restored log file "000000010000000000000003" from archive
    2016-01-22 23:06:55 CET [8062-4] LOG:  redo starts at 0/3000090
    2016-01-22 23:06:55 CET [8062-5] LOG:  restored log file "000000010000000000000004" from archive
    2016-01-22 23:06:55 CET [8062-6] LOG:  consistent recovery state reached at 0/4000050
    2016-01-22 23:06:55 CET [8062-7] LOG:  restored log file "000000010000000000000005" from archive
    2016-01-22 23:06:55 CET [8062-8] LOG:  redo done at 0/5010A20
    2016-01-22 23:06:55 CET [8062-9] LOG:  last completed transaction was at log time 2016-01-22 23:05:01.436339+01
    2016-01-22 23:06:56 CET [8062-10] LOG:  restored log file "000000010000000000000005" from archive
    2016-01-22 23:06:56 CET [8062-11] LOG:  selected new timeline ID: 2
    2016-01-22 23:06:57 CET [8062-12] LOG:  archive recovery complete
    2016-01-22 23:06:57 CET [8062-13] LOG:  MultiXact member wraparound protections are now enabled

#### Recovery process - restore to the named restore point ####

Create named restore point using the following function.

postgres@debian:~$ psql -A -t -c "select pg_create_restore_point('Restore point before important operation');"
    0/50000F8

This solution is available since *PostgreSQL 9.1*.

Stop database server.

postgres@debian:~$ pg_ctlcluster 9.4 main stop

Backup current database files.

postgres@debian:~$ mv /var/lib/postgresql/9.4/main /var/lib/postgresql/9.4/main.before_recovery

Copy archived database files.

postgres@debian:~$ cp -rp /var/lib/postgresql/archive/base /var/lib/postgresql/9.4/main

Create recovery file to restore database the named restore point specified by `recovery_target_name`directive.

Start the database server to perform recovery.

postgres@debian:~$ pg_ctlcluster 9.4 main start

Monitor recovery process.

postgres@debian:~$ tail -f /var/log/postgresql/postgresql-9.4-main.log

2016-01-23 02:03:58 CET [10929-1] LOG:  database system was interrupted; last known up at 2016-01-23 01:54:31 CET
    2016-01-23 02:03:58 CET [10929-2] LOG:  creating missing WAL directory "pg_xlog/archive_status"
    2016-01-23 02:03:58 CET [10929-3] LOG:  starting point-in-time recovery to "Restore point before important operation"
    2016-01-23 02:03:58 CET [10929-4] LOG:  restored log file "000000010000000000000002" from archive
    2016-01-23 02:03:58 CET [10929-5] LOG:  redo starts at 0/2000090
    2016-01-23 02:03:58 CET [10929-6] LOG:  consistent recovery state reached at 0/20000B8
    2016-01-23 02:03:58 CET [10929-7] LOG:  restored log file "000000010000000000000003" from archive
    2016-01-23 02:03:58 CET [10929-8] LOG:  restored log file "000000010000000000000004" from archive
    2016-01-23 02:03:58 CET [10929-9] LOG:  restored log file "000000010000000000000005" from archive
    2016-01-23 02:03:58 CET [10929-10] LOG:  recovery stopping at restore point "Restore point before important operation", time 2016-01-23 01:55:42.981348+01
    2016-01-23 02:03:58 CET [10929-11] LOG:  redo done at 0/5000090
    2016-01-23 02:03:58 CET [10929-12] LOG:  last completed transaction was at log time 2016-01-23 01:55:21.700315+01
    2016-01-23 02:03:58 CET [10929-13] LOG:  selected new timeline ID: 2
    sh: 1: cannot open /var/lib/postgresql/archive/wal/00000001.history.xz: No such file
    2016-01-23 02:04:00 CET [10929-14] LOG:  archive recovery complete
    2016-01-23 02:04:00 CET [10929-15] LOG:  MultiXact member wraparound protections are now enabled

#### Recovery process - restore to the specific point in time using hot standby mode ####

This solution requires `hot_standby` operation mode, so you need to specify proper format for archived **Write Ahead Log** file segments.

Change logging information from `archive` to `hot_standby` mode.

debian:~$ sudo sed -i -e "s/^wal_level = archive/wal_level = hot_standby/" /etc/postgresql/9.4/main/postgresql.conf

Enable `hot_standby` mode to allow queries during recovery process.

debian:~$ sudo sed -i -e "s/^#hot_standby = off/hot_standby = on/" /etc/postgresql/9.4/main/postgresql.conf

Restart database server.

postgres@debian:~$ pg_ctlcluster 9.4 main restart

Perform new backup at this moment as you need to have **Write Ahead Log** file segments using `hot_standby` logging information.

Stop database server.

postgres@debian:~$ pg_ctlcluster 9.4 main stop

Backup current database files.

postgres@debian:~$ mv /var/lib/postgresql/9.4/main /var/lib/postgresql/9.4/main.before_recovery

Copy archived database files.

postgres@debian:~$ cp -rp /var/lib/postgresql/archive/base /var/lib/postgresql/9.4/main

Create recovery file to restore database to specified point in time.

postgres@debian:~$ cat << EOF | tee /var/lib/postgresql/9.4/main/recovery.conf
    # provide missing wal file segments
    restore_command = 'xz --decompress < /var/lib/postgresql/archive/wal/%f.xz > %p'
    
    # recovery target time
    recovery_target_time='2016-01-22 23:05:10'
    
    # end recovery after reaching target time
    pause_at_recovery_target=true         # 9.4
    # recovery_target_action=pause        # 9.5
    
    # apply commits older than or equal to the target time
    recovery_target_inclusive = true
    EOF

Start the database server to perform recovery.

postgres@debian:~$ pg_ctlcluster 9.4 main start

Query database to verify desired state as it is working in **read-only** mode.

You can easily verify that database is in recovery mode.

postgres@debian:~$ psql  -A -t -c "select  pg_is_xlog_replay_paused()"
    t

**Update recovery target time** to new value to prepare for the next recovery step.

postgres@debian:~$ cat << EOF | tee /var/lib/postgresql/9.4/main/recovery.conf
    # provide missing wal file segments
    restore_command = 'xz --decompress < /var/lib/postgresql/archive/wal/%f.xz > %p'
    
    # recovery target time
    recovery_target_time='2016-01-23 00:05:00'
    
    # pause recovery after reaching target time
    pause_at_recovery_target=true         # 9.4
    # recovery_target_action=pause        # 9.5
    
    # apply commits older than or equal to the target time
    recovery_target_inclusive = true
    EOF

Restart the database server to continue recovery.

postgres@debian:~$ pg_ctlcluster 9.4 main restart

Repeat previous steps (*recovery target time* update and database restart) till you reach desired database state.

Restore normal operations after reaching desired database state.

postgres@debian:~$ psql -A -t -c "select pg_xlog_replay_resume()"

Monitor recovery process.

postgres@debian:~$ tail /var/log/postgresql/postgresql-9.4-main.log

2016-01-23 00:30:48 CET [10271-1] LOG:  database system was interrupted; last known up at 2016-01-22 23:58:03 CET
    2016-01-23 00:30:48 CET [10271-2] LOG:  creating missing WAL directory "pg_xlog/archive_status"
    2016-01-23 00:30:48 CET [10271-3] LOG:  starting point-in-time recovery to 2016-01-22 23:57:00+01
    2016-01-23 00:30:48 CET [10271-4] LOG:  restored log file "000000010000000000000002" from archive
    2016-01-23 00:30:48 CET [10271-5] LOG:  redo starts at 0/2000028
    2016-01-23 00:30:48 CET [10271-6] LOG:  consistent recovery state reached at 0/2000128
    2016-01-23 00:30:48 CET [10270-1] LOG:  database system is ready to accept read only connections
    2016-01-23 00:30:48 CET [10271-7] LOG:  restored log file "000000010000000000000003" from archive
    2016-01-23 00:30:48 CET [10271-8] LOG:  recovery stopping before commit of transaction 685, time 2016-01-22 23:58:48.268537+01
    2016-01-23 00:30:48 CET [10271-9] LOG:  recovery has paused
    2016-01-23 00:30:48 CET [10271-10] HINT:  Execute pg_xlog_replay_resume() to continue.
    2016-01-23 00:31:15 CET [10270-2] LOG:  received smart shutdown request
    2016-01-23 00:31:15 CET [10274-1] LOG:  shutting down
    2016-01-23 00:31:15 CET [10274-2] LOG:  database system is shut down
    2016-01-23 00:31:16 CET [10322-1] LOG:  database system was shut down in recovery at 2016-01-23 00:31:15 CET
    2016-01-23 00:31:16 CET [10322-2] LOG:  starting point-in-time recovery to 2016-01-22 23:58:00+01
    2016-01-23 00:31:16 CET [10322-3] LOG:  restored log file "000000010000000000000002" from archive
    2016-01-23 00:31:16 CET [10322-4] LOG:  redo starts at 0/2000028
    2016-01-23 00:31:16 CET [10322-5] LOG:  restored log file "000000010000000000000003" from archive
    2016-01-23 00:31:16 CET [10322-6] LOG:  consistent recovery state reached at 0/300F8B0
    2016-01-23 00:31:16 CET [10321-1] LOG:  database system is ready to accept read only connections
    2016-01-23 00:31:16 CET [10322-7] LOG:  recovery stopping before commit of transaction 685, time 2016-01-22 23:58:48.268537+01
    2016-01-23 00:31:16 CET [10322-8] LOG:  recovery has paused
    2016-01-23 00:31:16 CET [10322-9] HINT:  Execute pg_xlog_replay_resume() to continue.
    2016-01-23 00:31:52 CET [10321-2] LOG:  received smart shutdown request
    2016-01-23 00:31:52 CET [10325-1] LOG:  shutting down
    2016-01-23 00:31:52 CET [10325-2] LOG:  database system is shut down
    2016-01-23 00:31:53 CET [10361-1] LOG:  database system was shut down in recovery at 2016-01-23 00:31:52 CET
    2016-01-23 00:31:53 CET [10361-2] LOG:  starting point-in-time recovery to 2016-01-22 23:59:00+01
    2016-01-23 00:31:53 CET [10361-3] LOG:  restored log file "000000010000000000000002" from archive
    2016-01-23 00:31:53 CET [10361-4] LOG:  redo starts at 0/2000028
    2016-01-23 00:31:53 CET [10361-5] LOG:  restored log file "000000010000000000000003" from archive
    2016-01-23 00:31:53 CET [10361-6] LOG:  consistent recovery state reached at 0/300F8B0
    2016-01-23 00:31:53 CET [10360-1] LOG:  database system is ready to accept read only connections
    2016-01-23 00:31:53 CET [10361-7] LOG:  recovery stopping before commit of transaction 686, time 2016-01-23 00:02:33.477804+01
    2016-01-23 00:31:53 CET [10361-8] LOG:  recovery has paused
    2016-01-23 00:31:53 CET [10361-9] HINT:  Execute pg_xlog_replay_resume() to continue.
    2016-01-23 00:32:14 CET [10361-10] LOG:  redo done at 0/3010A28
    2016-01-23 00:32:14 CET [10361-11] LOG:  last completed transaction was at log time 2016-01-22 23:58:48.268537+01
    2016-01-23 00:32:14 CET [10361-12] LOG:  restored log file "00000002.history" from archive
    2016-01-23 00:32:14 CET [10361-13] LOG:  restored log file "00000003.history" from archive
    2016-01-23 00:32:14 CET [10361-14] LOG:  restored log file "00000004.history" from archive
    2016-01-23 00:32:14 CET [10361-15] LOG:  restored log file "00000005.history" from archive
    2016-01-23 00:32:14 CET [10361-16] LOG:  restored log file "00000006.history" from archive
    2016-01-23 00:32:14 CET [10361-17] LOG:  restored log file "00000007.history" from archive
    sh: 1: cannot open /var/lib/postgresql/archive/wal/00000008.history.xz: No such file
    2016-01-23 00:32:14 CET [10361-18] LOG:  selected new timeline ID: 8
    sh: 1: cannot open /var/lib/postgresql/archive/wal/00000001.history.xz: No such file
    2016-01-23 00:32:14 CET [10361-19] LOG:  archive recovery complete
    2016-01-23 00:32:14 CET [10361-20] LOG:  MultiXact member wraparound protections are now enabled
    2016-01-23 00:32:14 CET [10360-2] LOG:  database system is ready to accept connections
    2016-01-23 00:32:14 CET [10413-1] LOG:  autovacuum launcher started

#### Additional notes ####

There is more than that but now you can go one step further and inspect documentation.

#### References ####

[PostgreSQL Documentation → Backup and Restore][PostgreSQL Documentation _ Backup and Restore]

[PostgreSQL Documentation → Backup and Restore → Continuous Archiving and Point-in-Time Recovery (PITR) → Making a Base Backup Using the Low Level API][PostgreSQL Documentation _ Backup and Restore _ Continuous Archiving and Point-in-Time Recovery _PITR_ _ Making a Base Backup Using the Low Level API]

[PostgreSQL Documentation → Recovery Configuration → Archive recovery settings][PostgreSQL Documentation _ Recovery Configuration _ Archive recovery settings]

[PostgreSQL Documentation → Recovery Configuration → Recovery Target Settings][PostgreSQL Documentation _ Recovery Configuration _ Recovery Target Settings]

[Debian]: https://blog.sleeplessbeastie.eu/tags/index.html#Debian
[Jessie]: https://blog.sleeplessbeastie.eu/tags/index.html#Jessie
[PostgreSQL]: https://blog.sleeplessbeastie.eu/tags/index.html#PostgreSQL
[Initial notes]: https://blog.sleeplessbeastie.eu/2016/02/29/how-to-perform-postgresql-point-in-time-recovery/#a
[Database configuration]: https://blog.sleeplessbeastie.eu/2016/02/29/how-to-perform-postgresql-point-in-time-recovery/#b
[Create initial database backup]: https://blog.sleeplessbeastie.eu/2016/02/29/how-to-perform-postgresql-point-in-time-recovery/#c
[Recovery process - restore to the most recent state]: https://blog.sleeplessbeastie.eu/2016/02/29/how-to-perform-postgresql-point-in-time-recovery/#d
[Recovery process - restore to the specific point in time]: https://blog.sleeplessbeastie.eu/2016/02/29/how-to-perform-postgresql-point-in-time-recovery/#e
[Recovery process - restore to the named restore point]: https://blog.sleeplessbeastie.eu/2016/02/29/how-to-perform-postgresql-point-in-time-recovery/#f
[Recovery process - restore to the specific point in time using hot standby mode]: https://blog.sleeplessbeastie.eu/2016/02/29/how-to-perform-postgresql-point-in-time-recovery/#g
[Additional notes]: https://blog.sleeplessbeastie.eu/2016/02/29/how-to-perform-postgresql-point-in-time-recovery/#h
[References]: https://blog.sleeplessbeastie.eu/2016/02/29/how-to-perform-postgresql-point-in-time-recovery/#i
[rsync]: https://blog.sleeplessbeastie.eu/2013/08/08/how-to-perform-automated-backup-using-rsync-over-ssh/
[PostgreSQL Documentation _ Backup and Restore]: https://www.postgresql.org/docs/current/static/backup.html
[PostgreSQL Documentation _ Backup and Restore _ Continuous Archiving and Point-in-Time Recovery _PITR_ _ Making a Base Backup Using the Low Level API]: https://www.postgresql.org/docs/current/static/continuous-archiving.html#BACKUP-LOWLEVEL-BASE-BACKUP
[PostgreSQL Documentation _ Recovery Configuration _ Archive recovery settings]: https://www.postgresql.org/docs/current/static/archive-recovery-settings.html
[PostgreSQL Documentation _ Recovery Configuration _ Recovery Target Settings]: https://www.postgresql.org/docs/current/static/recovery-target-settings.html