Tag Archives: Linux PostgreSQL

Backup and Restore on Same Host Using pg_basebackup

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How to Backup and Restore PostgreSQL DB Cluster on the Same Host Using pg_basebackup

Table of Contents

1. Environment
2. Verify Existing DB Setup
3. Pre-requisites
4. Take Backup
5. Prepare & Restore
     5.1 Stop PostgreSQL and Clean Directories
     5.2 Remove all from Data & WAL directories
     5.3 Restore Data and WAL
         A. Copy Backup files to $PGDATA
         B. Copy WAL files from $PGDATA/pg_wal to /pgWal/pgsql17/wal/
         C. Remove the existing $PGDATA/pg_wal directory
         D. Create a symbolic link pointing $PGDATA/pg_wal to a separate WAL directory
         E. Set Permissions
6. Start PostgreSQL
7. Final Verification

1. Environment

ASPECTEnv
Hostnamelxicbpgdsgv01
IP Address192.168.2.51
OSRHEL 9
DB VersionPostgreSQL v17.6
Archive modearchive_mode=off
pgData/pgData/pgsql17/data
WAL Directory/pgWal/pgsql17/wal
Tablespacepg_default
DatabasesDELL, ORCL

2. Verify Existing DB Setup

[postgres@lxicbpgdsgv01 ~]$ psql
psql (17.6)
Type "help" for help.

postgres=# \l+
                                                                                       List of databases
   Name    |  Owner   | Encoding | Locale Provider |   Collate   |    Ctype    | Locale | ICU Rules |   Access privileges   |  Size   | Tablespace |                Description
-----------+----------+----------+-----------------+-------------+-------------+--------+-----------+-----------------------+---------+------------+--------------------------------------------
 dell      | postgres | UTF8     | libc            | en_SG.UTF-8 | en_SG.UTF-8 |        |           |                       | 7763 kB | pg_default |
 orcl      | postgres | UTF8     | libc            | en_SG.UTF-8 | en_SG.UTF-8 |        |           |                       | 7907 kB | pg_default |
 postgres  | postgres | UTF8     | libc            | en_SG.UTF-8 | en_SG.UTF-8 |        |           |                       | 492 MB  | pg_default | default administrative connection database
 template0 | postgres | UTF8     | libc            | en_SG.UTF-8 | en_SG.UTF-8 |        |           | =c/postgres          +| 7545 kB | pg_default | unmodifiable empty database
           |          |          |                 |             |             |        |           | postgres=CTc/postgres |         |            |
 template1 | postgres | UTF8     | libc            | en_SG.UTF-8 | en_SG.UTF-8 |        |           | =c/postgres          +| 7723 kB | pg_default | default template for new databases
           |          |          |                 |             |             |        |           | postgres=CTc/postgres |         |            |
(5 rows)

postgres=# \db
       List of tablespaces
    Name    |  Owner   | Location
------------+----------+----------
 pg_default | postgres |
 pg_global  | postgres |
(2 rows)

postgres=# \c dell
You are now connected to database "dell" as user "postgres".
dell=# select * from test.emp;
 name | designation | project | company
------+-------------+---------+---------
 Sugi | DBA         | Jetstar | iGATE
 Teja | DBA         | RCM     | iGATE
 RAJ  | DBA         | RCM     | iGATE
(3 rows)

dell=#

3. Pre-requisites

  • Verify postgresql.conf
postgres=# SHOW wal_level;
 wal_level
-----------
 replica <----
(1 row)

postgres=#
postgres=# SHOW max_wal_senders;
 max_wal_senders
-----------------
 10
(1 row)

postgres=# SHOW archive_mode;
 archive_mode
--------------
 off
(1 row)

postgres=#
  • Verify pg_hba.conf
# TYPE  DATABASE        USER            ADDRESS             METHOD
# Local connections for replication (for pg_basebackup run locally)
local   replication     all                                 trust

# Remote connections for replication (for pg_basebackup run remotely)
#host    replication     repl_user       192.168.2.52/32     scram-sha-256
  • Verify user permissions:REPLICATION or SUPERUSER required
postgres=# \du
                             List of roles
 Role name |                         Attributes
-----------+------------------------------------------------------------
 postgres  | Superuser, Create role, Create DB, Replication, Bypass RLS

postgres=#
  • Verify free space for backup
[postgres@lxicbpgdsgv01 ~]$ du -sh /pgData/pgsql17/data/
524M    /pgData/pgsql17/data/
[postgres@lxicbpgdsgv01 ~]$
[postgres@lxicbpgdsgv01 ~]$ du -sh /pgWal/pgsql17/wal/
801M    /pgWal/pgsql17/wal/
[postgres@lxicbpgdsgv01 ~]$

[postgres@lxicbpgdsgv01 ~]$ df -h /pgBackup/
Filesystem      Size  Used Avail Use% Mounted on
/dev/sdd1       100G  746M  100G   1% /pgBackup <----
[postgres@lxicbpgdsgv01 ~]$ mkdir -p /pgBackup/pgsql17/backup/basebackup_10OCT2025
[postgres@lxicbpgdsgv01 ~]$
[postgres@lxicbpgdsgv01 ~]$ mkdir -p /pgBackup/pgsql17/backup/log/
[postgres@lxicbpgdsgv01 ~]$

4. Take Backup

[postgres@lxicbpgdsgv01 ~]$ ls -ltrh /pgWal/pgsql17/wal | wc -l
53 <---- 
[postgres@lxicbpgdsgv01 ~]$

pg_basebackup does not include all files from the pg_wal directory in the backup. Instead, it selectively includes only the WAL files required to make the base backup consistent at the point in time the backup was taken.

-- If you want to store the base backup and WAL files in separate backup directories. 

nohup pg_basebackup -U postgres -D /pgBackup/pgsql17/backup/basebackup_10OCT2025 --waldir=/pgBackup/pgsql17/backup/wal_backup -Fp -Xs -P -v > /pgBackup/pgsql17/backup/log/basebackup_10OCT2025.log 2>&1 &

The --waldir option in pg_basebackup is supported only when using the plain format (-Fp), not with the tar format (-Ft).

If we want symlinks preserved → use (both -Fp & --waldir use together) -Fp --waldir=/pgWal/pgsql17/wal

-- OR --

The directory mush be empty: /pgBackup/pgsql17/backup/basebackup_10OCT2025

[postgres@lxicbpgdsgv01 ~]$ nohup pg_basebackup -U postgres -D /pgBackup/pgsql17/backup/basebackup_10OCT2025 -Fp -Xs -P -v > /pgBackup/pgsql17/backup/log/basebackup_10OCT2025.log 2>&1 &
[1] 4973
[postgres@lxicbpgdsgv01 ~]$

[postgres@lxicbpgdsgv01 ~]$ cat /pgBackup/pgsql17/backup/log/basebackup_10OCT2025.log
nohup: ignoring input
pg_basebackup: initiating base backup, waiting for checkpoint to complete
pg_basebackup: checkpoint completed
pg_basebackup: write-ahead log start point: 0/85000028 on timeline 1
pg_basebackup: starting background WAL receiver
pg_basebackup: created temporary replication slot "pg_basebackup_4975"
279413/536037 kB (52%), 0/1 tablespace (...asebackup_10OCT2025/base/5/16533)
536047/536047 kB (100%), 0/1 tablespace (...ckup_10OCT2025/global/pg_control)
536047/536047 kB (100%), 1/1 tablespace
pg_basebackup: write-ahead log end point: 0/85000158
pg_basebackup: waiting for background process to finish streaming ...
pg_basebackup: syncing data to disk ...
pg_basebackup: renaming backup_manifest.tmp to backup_manifest
pg_basebackup: base backup completed  <-----
[postgres@lxicbpgdsgv01 ~]$

5. Prepare & Restore

5.1 Stop PostgreSQL and Clean Directories

[root@lxicbpgdsgv01 ~]# systemctl stop postgresql-17.service
[root@lxicbpgdsgv01 ~]# 
[root@lxicbpgdsgv01 ~]# ps -ef | grep postgres
root        5057    3151  0 18:57 pts/0    00:00:00 grep --color=auto postgres
[root@lxicbpgdsgv01 ~]#

5.2 Remove all from Data & WAL directories

-- Remove all from PGDATA directory

[root@lxicbpgdsgv01 ~]# rm -rf /pgData/pgsql17/data/*
[root@lxicbpgdsgv01 ~]# ls -ltr /pgData/pgsql17/data/
total 0
[root@lxicbpgdsgv01 ~]#

-- Remove all from WAL directory 

[root@lxicbpgdsgv01 ~]# rm -rf /pgWal/pgsql17/wal/*
[root@lxicbpgdsgv01 ~]# ls -ltr /pgWal/pgsql17/wal/
total 0
[root@lxicbpgdsgv01 ~]#

5.3 Restore Data and WAL

A. Copy Backup files to $PGDATA
Since we did not use the -Fp format with the --waldir option, all required WAL files will be included in the backup under the default path: PGDATA/pg_wal.

[postgres@lxicbpgdsgv01 ~]$ ls -ltr /pgData/pgsql17/data/
total 0
[postgres@lxicbpgdsgv01 ~]$ cd /pgBackup/pgsql17/backup/basebackup_10OCT2025/
[postgres@lxicbpgdsgv01 basebackup_10OCT2025]$ cp -Rp * /pgData/pgsql17/data/
[postgres@lxicbpgdsgv01 basebackup_10OCT2025]$
[postgres@lxicbpgdsgv01 basebackup_10OCT2025]$ ls -ltr /pgData/pgsql17/data/
total 296
-rw-------. 1 postgres postgres    227 Oct 10 18:41 backup_label
drwx------. 4 postgres postgres     77 Oct 10 18:41 pg_wal
drwx------. 7 postgres postgres     59 Oct 10 18:41 base
drwx------. 4 postgres postgres     68 Oct 10 18:41 pg_logical
drwx------. 2 postgres postgres      6 Oct 10 18:41 pg_dynshmem
drwx------. 2 postgres postgres      6 Oct 10 18:41 pg_commit_ts
drwx------. 2 postgres postgres    110 Oct 10 18:41 log
-rw-------. 1 postgres postgres   1169 Oct 10 18:41 postgresql.conf.bkp_10sep2025
-rw-------. 1 postgres postgres  30702 Oct 10 18:41 postgresql.conf.bkp
-rw-------. 1 postgres postgres     88 Oct 10 18:41 postgresql.auto.conf
drwx------. 2 postgres postgres     18 Oct 10 18:41 pg_xact
-rw-------. 1 postgres postgres      3 Oct 10 18:41 PG_VERSION
drwx------. 2 postgres postgres      6 Oct 10 18:41 pg_twophase
drwx------. 2 postgres postgres      6 Oct 10 18:41 pg_tblspc
drwx------. 2 postgres postgres      6 Oct 10 18:41 pg_subtrans
drwx------. 2 postgres postgres      6 Oct 10 18:41 pg_stat_tmp
drwx------. 2 postgres postgres      6 Oct 10 18:41 pg_stat
drwx------. 2 postgres postgres      6 Oct 10 18:41 pg_snapshots
drwx------. 2 postgres postgres      6 Oct 10 18:41 pg_serial
drwx------. 2 postgres postgres      6 Oct 10 18:41 pg_replslot
drwx------. 2 postgres postgres      6 Oct 10 18:41 pg_notify
drwx------. 4 postgres postgres     36 Oct 10 18:41 pg_multixact
-rw-------. 1 postgres postgres   2640 Oct 10 18:41 pg_ident.conf
-rw-------. 1 postgres postgres   5600 Oct 10 18:41 pg_hba.conf
-rw-------. 1 postgres postgres   1171 Oct 10 18:41 postgresql.conf
drwx------. 2 postgres postgres   4096 Oct 10 18:41 global
-rw-------. 1 postgres postgres     30 Oct 10 18:41 current_logfiles
-rw-------. 1 postgres postgres 227736 Oct 10 18:41 backup_manifest
[postgres@lxicbpgdsgv01 basebackup_10OCT2025]$
B. Copy WAL files from $PGDATA/pg_wal to /pgWal/pgsql17/wal/
[postgres@lxicbpgdsgv01 ~]$ ls -ltr /pgWal/pgsql17/wal/
total 0
[postgres@lxicbpgdsgv01 ~]$
[postgres@lxicbpgdsgv01 ~]$ cd /pgData/pgsql17/data/pg_wal/
[postgres@lxicbpgdsgv01 pg_wal]$ cp -Rp * /pgWal/pgsql17/wal
[postgres@lxicbpgdsgv01 pg_wal]$
[postgres@lxicbpgdsgv01 pg_wal]$ ls -ltr /pgWal/pgsql17/wal
total 16384
drwx------. 2 postgres postgres        6 Oct 10 18:41 summaries
drwx------. 2 postgres postgres        6 Oct 10 18:41 archive_status
-rw-------. 1 postgres postgres 16777216 Oct 10 18:41 000000010000000000000085
[postgres@lxicbpgdsgv01 pg_wal]$ cd
[postgres@lxicbpgdsgv01 ~]$
C. Remove the existing $PGDATA/pg_wal directory
[postgres@lxicbpgdsgv01 ~]$ rm -rf /pgData/pgsql17/data/pg_wal
[postgres@lxicbpgdsgv01 ~]$
D. Create a symbolic link pointing $PGDATA/pg_wal to a separate WAL directory
[postgres@lxicbpgdsgv01 ~]$ ln -s /pgWal/pgsql17/wal /pgData/pgsql17/data/pg_wal
[postgres@lxicbpgdsgv01 ~]$
[postgres@lxicbpgdsgv01 ~]$ ls -ld /pgData/pgsql17/data/pg_wal
lrwxrwxrwx. 1 postgres postgres 18 Oct 10 19:43 /pgData/pgsql17/data/pg_wal -> /pgWal/pgsql17/wal
[postgres@lxicbpgdsgv01 ~]$
E. Set Permissions
[postgres@lxicbpgdsgv01 ~]$ chown -R postgres:postgres /pgData/pgsql17/data
[postgres@lxicbpgdsgv01 ~]$ chmod 700 /pgData/pgsql17/data
[postgres@lxicbpgdsgv01 ~]$ chown -R postgres:postgres /pgWal/pgsql17/wal
[postgres@lxicbpgdsgv01 ~]$ chmod 700 /pgWal/pgsql17/wal

6. Start PostgreSQL

[root@lxicbpgdsgv01 ~]# systemctl start postgresql-17.service
[root@lxicbpgdsgv01 ~]# systemctl status postgresql-17.service
● postgresql-17.service - PostgreSQL 17 database server
     Loaded: loaded (/usr/lib/systemd/system/postgresql-17.service; enabled; preset: disabled)
     Active: active (running) since Fri 2025-10-10 19:45:21 +08; 5s ago
       Docs: https://www.postgresql.org/docs/17/static/
    Process: 5230 ExecStartPre=/usr/pgsql-17/bin/postgresql-17-check-db-dir ${PGDATA} (code=exited, status=0/SUCCESS)
   Main PID: 5235 (postgres)
      Tasks: 7 (limit: 15835)
     Memory: 34.2M
        CPU: 94ms
     CGroup: /system.slice/postgresql-17.service
             ├─5235 /usr/pgsql-17/bin/postgres -D /pgData/pgsql17/data/
             ├─5236 "postgres: logger "
             ├─5237 "postgres: checkpointer "
             ├─5238 "postgres: background writer "
             ├─5240 "postgres: walwriter "
             ├─5241 "postgres: autovacuum launcher "
             └─5242 "postgres: logical replication launcher "

Oct 10 19:45:21 lxicbpgdsgv01.rajasekhar.com systemd[1]: Starting PostgreSQL 17 database server...
Oct 10 19:45:21 lxicbpgdsgv01.rajasekhar.com postgres[5235]: 2025-10-10 19:45:21.177 +08 [5235] LOG:  redirecting log output to logging collector process
Oct 10 19:45:21 lxicbpgdsgv01.rajasekhar.com postgres[5235]: 2025-10-10 19:45:21.177 +08 [5235] HINT:  Future log output will appear in directory "log".
Oct 10 19:45:21 lxicbpgdsgv01.rajasekhar.com systemd[1]: Started PostgreSQL 17 database server.
[root@lxicbpgdsgv01 ~]#

7. Final Verification

[postgres@lxicbpgdsgv01 ~]$ psql
psql (17.6)
Type "help" for help.

postgres=# \l+
                                                                                       List of databases
   Name    |  Owner   | Encoding | Locale Provider |   Collate   |    Ctype    | Locale | ICU Rules |   Access privileges   |  Size   | Tablespace |                Description
-----------+----------+----------+-----------------+-------------+-------------+--------+-----------+-----------------------+---------+------------+--------------------------------------------
 dell      | postgres | UTF8     | libc            | en_SG.UTF-8 | en_SG.UTF-8 |        |           |                       | 7609 kB | pg_default |
 orcl      | postgres | UTF8     | libc            | en_SG.UTF-8 | en_SG.UTF-8 |        |           |                       | 7753 kB | pg_default |
 postgres  | postgres | UTF8     | libc            | en_SG.UTF-8 | en_SG.UTF-8 |        |           |                       | 492 MB  | pg_default | default administrative connection database
 template0 | postgres | UTF8     | libc            | en_SG.UTF-8 | en_SG.UTF-8 |        |           | =c/postgres          +| 7545 kB | pg_default | unmodifiable empty database
           |          |          |                 |             |             |        |           | postgres=CTc/postgres |         |            |
 template1 | postgres | UTF8     | libc            | en_SG.UTF-8 | en_SG.UTF-8 |        |           | =c/postgres          +| 7569 kB | pg_default | default template for new databases
           |          |          |                 |             |             |        |           | postgres=CTc/postgres |         |            |
(5 rows)

postgres=# \db
       List of tablespaces
    Name    |  Owner   | Location
------------+----------+----------
 pg_default | postgres |
 pg_global  | postgres |
(2 rows)

postgres=# \c dell
You are now connected to database "dell" as user "postgres".
dell=# select * from test.emp;
 name | designation | project | company
------+-------------+---------+---------
 Sugi | DBA         | Jetstar | iGATE
 Teja | DBA         | RCM     | iGATE
 RAJ  | DBA         | RCM     | iGATE
(3 rows)

dell=#

Caution: Your use of any information or materials on this website is entirely at your own risk. It is provided for educational purposes only. It has been tested internally, however, we do not guarantee that it will work for you. Ensure that you run it in your test environment before using.

Thank you,
Rajasekhar Amudala
Email: br8dba@gmail.com
Linkedin: https://www.linkedin.com/in/rajasekhar-amudala/

Change PostgreSQL WAL Directory Path (pg_wal)

PostgreSQL, , , , , , , , , , , , , , , ,

Table of Contents

0. Aim
1. Verify Existing pg_wal Directory
2. Create the New Directory
3. Stop PostgreSQL Service
4. Copy WAL Files to New Location
5. Backup Old WAL Directory
6. Create Symlink
7. Fix Permissions
8. Start PostgreSQL Service
9. Verify WAL Functionality
10. Remove Old WAL Directory (Optional)

0. Aim

To change the PostgreSQL 17 WAL File directory from its default location to new mount point

From : /var/lib/pgsql/17/data

TO : /pgData/pgsql17/data

1. Verify Existing pg_wal directory


[postgres@lxicbpgdsgv01 ~]$ psql
psql (17.6)
Type "help" for help.

postgres=# SELECT current_setting('data_directory') || '/pg_wal' AS wal_directory;
        wal_directory
-----------------------------
 /pgData/pgsql17/data/pg_wal  <----- 
(1 row)

postgres=# exit
[postgres@lxicbpgdsgv01 ~]$ ls -lrth /pgData/pgsql17/data/pg_wal
total 48M
drwx------. 2 postgres postgres   6 Sep 30 21:50 summaries
-rw-------. 1 postgres postgres 16M Oct  8 04:24 000000010000000000000008
-rw-------. 1 postgres postgres 16M Oct  8 16:08 000000010000000000000006
-rw-------. 1 postgres postgres 16M Oct  8 16:08 000000010000000000000007
drwx------. 2 postgres postgres  43 Oct  8 16:08 archive_status
[postgres@lxicbpgdsgv01 ~]$

[postgres@lxicbpgdsgv01 ~]$ du -sh /pgData/pgsql17/data/pg_wal
48M     /pgData/pgsql17/data/pg_wal
[postgres@lxicbpgdsgv01 ~]$

2. Create the New Directory on a new disk

[root@lxicbpgdsgv01 ~]# mkdir -p /pgData/pgsql17/data
[root@lxicbpgdsgv01 ~]# chown postgres:postgres /pgData/pgsql17/data
[root@lxicbpgdsgv01 ~]# chmod 700 /pgData/pgsql17/data
[root@lxicbpgdsgv01 ~]#

3. Stop PostgreSQL Service

[root@lxicbpgdsgv01 ~]# systemctl stop postgresql-17.service
[root@lxicbpgdsgv01 ~]#
[root@lxicbpgdsgv01 ~]# ps -ef | grep postgres
root        6887    6721  0 16:08 pts/0    00:00:00 grep --color=auto postgres
[root@lxicbpgdsgv01 ~]#

4. Copy Existing WAL Files to New Location

[postgres@lxicbpgdsgv01 ~]$ nohup rsync -avh --progress /pgData/pgsql17/data/pg_wal/ /pgWal/pgsql17/wal/ > rsync_pgwal.log 2>&1 &
[1] 6943
[postgres@lxicbpgdsgv01 ~]$
[postgres@lxicbpgdsgv01 ~]$
[1]+  Done                    nohup rsync -avh --progress /pgData/pgsql17/data/pg_wal/ /pgWal/pgsql17/wal/ > rsync_pgwal.log 2>&1
[postgres@lxicbpgdsgv01 ~]$

[postgres@lxicbpgdsgv01 ~]$ cat rsync_pgwal.log
nohup: ignoring input
sending incremental file list
./
000000010000000000000006
         16.78M 100%   81.89MB/s    0:00:00 (xfr#1, to-chk=5/7)
000000010000000000000007
         16.78M 100%   43.84MB/s    0:00:00 (xfr#2, to-chk=4/7)
000000010000000000000008
         16.78M 100%   31.07MB/s    0:00:00 (xfr#3, to-chk=3/7)
archive_status/
archive_status/000000010000000000000006.done
              0 100%    0.00kB/s    0:00:00 (xfr#4, to-chk=0/7)
summaries/

sent 50.34M bytes  received 107 bytes  33.56M bytes/sec
total size is 50.33M  speedup is 1.00
[postgres@lxicbpgdsgv01 ~]$

[postgres@lxicbpgdsgv01 ~]$ ls -lrth /pgWal/pgsql17/wal/
total 48M
drwx------. 2 postgres postgres   6 Sep 30 21:50 summaries
-rw-------. 1 postgres postgres 16M Oct  8 04:24 000000010000000000000008
-rw-------. 1 postgres postgres 16M Oct  8 16:08 000000010000000000000006
-rw-------. 1 postgres postgres 16M Oct  8 16:08 000000010000000000000007
drwx------. 2 postgres postgres  43 Oct  8 16:08 archive_status
[postgres@lxicbpgdsgv01 ~]$

[postgres@lxicbpgdsgv01 ~]$ du -sh /pgWal/pgsql17/wal/
48M     /pgWal/pgsql17/wal/
[postgres@lxicbpgdsgv01 ~]$

5. Move old directory as backup

[postgres@lxicbpgdsgv01 ~]$ mv /pgData/pgsql17/data/pg_wal /pgData/pgsql17/data/pg_wal.bak
[postgres@lxicbpgdsgv01 ~]$

[postgres@lxicbpgdsgv01 ~]$ ls -ld /pgData/pgsql17/data/pg_wal
ls: cannot access '/pgData/pgsql17/data/pg_wal': No such file or directory
[postgres@lxicbpgdsgv01 ~]$

[postgres@lxicbpgdsgv01 ~]$ ls -ld /pgData/pgsql17/data/pg_wal.bak
drwx------. 4 postgres postgres 141 Oct  8 16:08 /pgData/pgsql17/data/pg_wal.bak
[postgres@lxicbpgdsgv01 ~]$

6. Create symlink

[postgres@lxicbpgdsgv01 ~]$ ln -s /pgWal/pgsql17/wal /pgData/pgsql17/data/pg_wal
[postgres@lxicbpgdsgv01 ~]$
[postgres@lxicbpgdsgv01 ~]$ ls -ltr /pgData/pgsql17/data/pg_wal
lrwxrwxrwx. 1 postgres postgres 18 Oct  8 16:16 /pgData/pgsql17/data/pg_wal -> /pgWal/pgsql17/wal
[postgres@lxicbpgdsgv01 ~]$

7. Fix permissions (if required)

[postgres@lxicbpgdsgv01 ~]$ chown -R postgres:postgres /pgWal/pgsql17/wal

8. Start PostgreSQL Service

[root@lxicbpgdsgv01 ~]# systemctl start postgresql-17.service
[root@lxicbpgdsgv01 ~]#
[root@lxicbpgdsgv01 ~]# systemctl status postgresql-17.service
● postgresql-17.service - PostgreSQL 17 database server
     Loaded: loaded (/usr/lib/systemd/system/postgresql-17.service; enabled; preset: disabled)
     Active: active (running) since Wed 2025-10-08 16:20:46 +08; 7s ago
       Docs: https://www.postgresql.org/docs/17/static/
    Process: 7079 ExecStartPre=/usr/pgsql-17/bin/postgresql-17-check-db-dir ${PGDATA} (code=exited, status=0/SUCCESS)
   Main PID: 7084 (postgres)
      Tasks: 8 (limit: 15835)
     Memory: 18.1M
        CPU: 94ms
     CGroup: /system.slice/postgresql-17.service
             ├─7084 /usr/pgsql-17/bin/postgres -D /pgData/pgsql17/data/
             ├─7086 "postgres: logger "
             ├─7087 "postgres: checkpointer "
             ├─7088 "postgres: background writer "
             ├─7090 "postgres: walwriter "
             ├─7091 "postgres: autovacuum launcher "
             ├─7092 "postgres: archiver "
             └─7093 "postgres: logical replication launcher "

Oct 08 16:20:46 lxicbpgdsgv01.rajasekhar.com systemd[1]: Starting PostgreSQL 17 database server...
Oct 08 16:20:46 lxicbpgdsgv01.rajasekhar.com postgres[7084]: 2025-10-08 16:20:46.162 +08 [7084] LOG:  redirecting log output to logging collector process
Oct 08 16:20:46 lxicbpgdsgv01.rajasekhar.com postgres[7084]: 2025-10-08 16:20:46.162 +08 [7084] HINT:  Future log output will appear in directory "log".
Oct 08 16:20:46 lxicbpgdsgv01.rajasekhar.com systemd[1]: Started PostgreSQL 17 database server.
[root@lxicbpgdsgv01 ~]#

9. Verify

-- Load WAL File generation (Testing)

postgres=# -- Create test table
DROP TABLE IF EXISTS wal_test;
CREATE TABLE wal_test (
    id serial PRIMARY KEY,
    data text
);

-- Generate WAL traffic
DO $$
DECLARE
    i integer;
BEGIN
    FOR i IN 1..50 LOOP
        -- INSERT: 10,000 rows
        INSERT INTO wal_test (data)
        SELECT repeat('wal_test_data_', 50)
        FROM generate_series(1, 10000);

        -- UPDATE: 5,000 rows using CTE with LIMIT
        WITH to_update AS (
            SELECT id FROM wal_test WHERE id % 2 = 0 LIMIT 5000
        )
        UPDATE wal_test
        SET data = data || '_updated'
        WHERE id IN (SELECT id FROM to_update);

        -- DELETE: 5,000 rows using CTE with LIMIT
        WITH to_delete AS (
            SELECT id FROM wal_test WHERE id % 3 = 0 LIMIT 5000
        )
        DELETE FROM wal_test
        WHERE id IN (SELECT id FROM to_delete);

        -- Commit to flush WAL
        COMMIT;

        -- Optional pause to slow down the loop
        PERFORM pg_sleep(0.5);
    END LOOP;
END$$;
DROP TABLE
CREATE TABLE
DO
postgres=# exit
[postgres@lxicbpgdsgv01 ~]$
[postgres@lxicbpgdsgv01 ~]$ ls -lrth  /pgWal/pgsql17/wal
total 752M
drwx------. 2 postgres postgres    6 Sep 30 21:50 summaries
-rw-------. 1 postgres postgres  16M Oct  8 16:34 000000010000000000000009
-rw-------. 1 postgres postgres  16M Oct  8 16:34 00000001000000000000000A
-rw-------. 1 postgres postgres  16M Oct  8 16:34 00000001000000000000000B
-rw-------. 1 postgres postgres  16M Oct  8 16:34 00000001000000000000000C
-rw-------. 1 postgres postgres  16M Oct  8 16:34 00000001000000000000000D
-rw-------. 1 postgres postgres  16M Oct  8 16:34 00000001000000000000000E
-rw-------. 1 postgres postgres  16M Oct  8 16:34 00000001000000000000000F
-rw-------. 1 postgres postgres  16M Oct  8 16:34 000000010000000000000010
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000011
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000012
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000013
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000014
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000015
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000016
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000017
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000018
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000019
-rw-------. 1 postgres postgres  16M Oct  8 16:35 00000001000000000000001A
-rw-------. 1 postgres postgres  16M Oct  8 16:35 00000001000000000000001B
-rw-------. 1 postgres postgres  16M Oct  8 16:35 00000001000000000000001C
-rw-------. 1 postgres postgres  16M Oct  8 16:35 00000001000000000000001D
-rw-------. 1 postgres postgres  16M Oct  8 16:35 00000001000000000000001E
-rw-------. 1 postgres postgres  16M Oct  8 16:35 00000001000000000000001F
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000020
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000021
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000022
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000023
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000024
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000025
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000026
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000027
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000028
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000029
-rw-------. 1 postgres postgres  16M Oct  8 16:35 00000001000000000000002A
-rw-------. 1 postgres postgres  16M Oct  8 16:35 00000001000000000000002B
-rw-------. 1 postgres postgres  16M Oct  8 16:35 00000001000000000000002C
-rw-------. 1 postgres postgres  16M Oct  8 16:35 00000001000000000000002D
-rw-------. 1 postgres postgres  16M Oct  8 16:35 00000001000000000000002E
-rw-------. 1 postgres postgres  16M Oct  8 16:35 00000001000000000000002F
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000030
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000031
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000032
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000033
-rw-------. 1 postgres postgres  16M Oct  8 16:35 000000010000000000000034
-rw-------. 1 postgres postgres  16M Oct  8 16:36 000000010000000000000035
drwx------. 2 postgres postgres 4.0K Oct  8 16:36 archive_status
-rw-------. 1 postgres postgres  16M Oct  8 16:36 xlogtemp.7289
[postgres@lxicbpgdsgv01 ~]$

10. Remove Old WAL Directory (Optional, later)

[postgres@lxicbpgdsgv01 ~]$ ls -ld /pgData/pgsql17/data/pg_wal.bak
drwx------. 4 postgres postgres 141 Oct  8 16:08 /pgData/pgsql17/data/pg_wal.bak
[postgres@lxicbpgdsgv01 ~]$ rm -rf /pgData/pgsql17/data/pg_wal.bak
[postgres@lxicbpgdsgv01 ~]$

Caution: Your use of any information or materials on this website is entirely at your own risk. It is provided for educational purposes only. It has been tested internally, however, we do not guarantee that it will work for you. Ensure that you run it in your test environment before using.

Thank you,
Rajasekhar Amudala
Email: br8dba@gmail.com
Linkedin: https://www.linkedin.com/in/rajasekhar-amudala/

Change Data Directory

PostgreSQL, , , , , , , , , , , , , , , , , , , , , , , ,

PostgreSQL 17 – Change Data Directory

0. Overview
1. Stop PostgreSQL Service
2. Create the New Directory
3. Copy Existing Data to New Location
4. Move existing data directory
5. Update PostgreSQL Configuration to Use New Data Directory
6. Reload systemd and start PostgreSQL
7. Edit postgres .bash_profile
8. Verify New Data Directory is in Use
9. Remove Old Data Directory (Optional – A week after)

0. Overview

To change the PostgreSQL 17 data directory from its default location

From: /var/lib/pgsql/17/data To: /pgData/pgsql17/data

 

1. Stop PostgreSQL Service

[postgres@lxicbpgdsgv01 ~]$ psql -c "SHOW data_directory;"
     data_directory
------------------------
 /var/lib/pgsql/17/data <---- existing data directory
(1 row)

[postgres@lxicbpgdsgv01 ~]$

[root@lxicbpgdsgv01 ~]# systemctl stop postgresql-17
[root@lxicbpgdsgv01 ~]# 
[root@lxicbpgdsgv01 ~]# ps -ef | grep postgres
root        5759    4079  0 18:09 pts/1    00:00:00 grep --color=auto postgres
[root@lxicbpgdsgv01 ~]#

2. Create the New Directory

[root@lxicbpgdsgv01 ~]# mkdir -p /pgData/pgsql17/data
[root@lxicbpgdsgv01 ~]# chown postgres:postgres /pgData/pgsql17/data
[root@lxicbpgdsgv01 ~]# chmod 700 /pgData/pgsql17/data
[root@lxicbpgdsgv01 ~]#

3. Copy Existing Data to New Location

[postgres@lxicbpgdsgv01 ~]$ nohup rsync -av --progress /var/lib/pgsql/17/data/ /pgData/pgsql17/data/ > rsync_pgdata.log 2>&1 &
[1] 5863
[postgres@lxicbpgdsgv01 ~]$

[postgres@lxicbpgdsgv01 ~]$ tail -f rsync_pgdata.log
pg_wal/000000010000000000000002
     16,777,216 100%   17.68MB/s    0:00:00 (xfr#1621, to-chk=3/1652)
pg_wal/archive_status/
pg_wal/summaries/
pg_xact/
pg_xact/0000
          8,192 100%    8.84kB/s    0:00:00 (xfr#1622, to-chk=0/1652)

sent 73,827,441 bytes  received 31,005 bytes  49,238,964.00 bytes/sec
total size is 73,717,583  speedup is 1.00
^C[1]+  Done                    nohup rsync -av --progress /var/lib/pgsql/17/data/ /pgData/pgsql17/data/ > rsync_pgdata.log 2>&1

[postgres@lxicbpgdsgv01 ~]$

4. Move existing data directory

[postgres@lxicbpgdsgv01 ~]$ mv /var/lib/pgsql/17/data /var/lib/pgsql/17/data_bkp_10072025
[postgres@lxicbpgdsgv01 ~]$

5. Update PostgreSQL Configuration to Use New Data Directory

[postgres@lxicbpgdsgv01 ~]$ cat /usr/lib/systemd/system/postgresql-17.service | grep -i "Environment=PGDATA"
Environment=PGDATA=/var/lib/pgsql/17/data/  <-----
[postgres@lxicbpgdsgv01 ~]$

[root@lxicbpgdsgv01 ~]# ls -ltr /usr/lib/systemd/system/postgresql-17.service
-rw-r--r--. 1 root root 1788 Aug 13 17:39 /usr/lib/systemd/system/postgresql-17.service
[root@lxicbpgdsgv01 ~]#

[root@lxicbpgdsgv01 ~]# sed -i 's|^Environment=PGDATA=.*|Environment=PGDATA=/pgData/pgsql17/data/|' /usr/lib/systemd/system/postgresql-17.service
[root@lxicbpgdsgv01 ~]#
[root@lxicbpgdsgv01 ~]# cat /usr/lib/systemd/system/postgresql-17.service | grep -i "Environment=PGDATA"
Environment=PGDATA=/pgData/pgsql17/data/ <------
[root@lxicbpgdsgv01 ~]#

6. Reload systemd and start PostgreSQL

[root@lxicbpgdsgv01 ~]# systemctl daemon-reload
[root@lxicbpgdsgv01 ~]#

[root@lxicbpgdsgv01 ~]# systemctl start postgresql-17
[root@lxicbpgdsgv01 ~]#

[root@lxicbpgdsgv01 ~]# systemctl cat postgresql-17 | grep -i Environment=PGDATA
Environment=PGDATA=/pgData/pgsql17/data/ <-----
[root@lxicbpgdsgv01 ~]#

[root@lxicbpgdsgv01 ~]# systemctl status postgresql-17
● postgresql-17.service - PostgreSQL 17 database server
     Loaded: loaded (/usr/lib/systemd/system/postgresql-17.service; enabled; preset: disabled)
     Active: active (running) since Tue 2025-10-07 18:33:05 +08; 2min 26s ago
       Docs: https://www.postgresql.org/docs/17/static/
    Process: 5911 ExecStartPre=/usr/pgsql-17/bin/postgresql-17-check-db-dir ${PGDATA} (code=exited, status=0/SUCCESS)
   Main PID: 5916 (postgres)
      Tasks: 7 (limit: 15700)
     Memory: 21.3M
        CPU: 177ms
     CGroup: /system.slice/postgresql-17.service
             ├─5916 /usr/pgsql-17/bin/postgres -D /pgData/pgsql17/data/
             ├─5917 "postgres: logger "
             ├─5918 "postgres: checkpointer "
             ├─5919 "postgres: background writer "
             ├─5921 "postgres: walwriter "
             ├─5922 "postgres: autovacuum launcher "
             └─5923 "postgres: logical replication launcher "

Oct 07 18:33:05 lxicbpgdsgv01.rajasekhar.com systemd[1]: Starting PostgreSQL 17 database server...
Oct 07 18:33:05 lxicbpgdsgv01.rajasekhar.com postgres[5916]: 2025-10-07 18:33:05.392 +08 [5916] LOG:  redirecting log output to logging collector process
Oct 07 18:33:05 lxicbpgdsgv01.rajasekhar.com postgres[5916]: 2025-10-07 18:33:05.392 +08 [5916] HINT:  Future log output will appear in directory "log".
Oct 07 18:33:05 lxicbpgdsgv01.rajasekhar.com systemd[1]: Started PostgreSQL 17 database server.

7. Edit postgres .bash_profile

[postgres@lxicbpgdsgv01 ~]$ cat .bash_profile | grep -i PGDATA=
PGDATA=/var/lib/pgsql/17/data
[postgres@lxicbpgdsgv01 ~]$

[postgres@lxicbpgdsgv01 ~]$ sed -i 's|^PGDATA=.*|PGDATA=/pgData/pgsql17/data|' ~/.bash_profile
[postgres@lxicbpgdsgv01 ~]$
[postgres@lxicbpgdsgv01 ~]$ cat .bash_profile | grep -i PGDATA=
PGDATA=/pgData/pgsql17/data <-----
[postgres@lxicbpgdsgv01 ~]$ . .bash_profile <-- reload the profile
[postgres@lxicbpgdsgv01 ~]$

8. Verify New Data Directory is in Use

[postgres@lxicbpgdsgv01 ~]$ psql -c "SHOW data_directory;"
    data_directory
----------------------
 /pgData/pgsql17/data  <---- new data directory
(1 row)

[postgres@lxicbpgdsgv01 ~]$

9. Remove Old Data Directory (Optional – A week after)

[postgres@lxicbpgdsgv01 ~]$ ls -ld /var/lib/pgsql/17/data_bkp_10072025
drwx------. 20 postgres postgres 4096 Oct  7 18:20 /var/lib/pgsql/17/data_bkp_10072025
[postgres@lxicbpgdsgv01 ~]$ rm -rf /var/lib/pgsql/17/data_bkp_10072025
[postgres@lxicbpgdsgv01 ~]$

 

Caution: Your use of any information or materials on this website is entirely at your own risk. It is provided for educational purposes only. It has been tested internally, however, we do not guarantee that it will work for you. Ensure that you run it in your test environment before using.

Thank you,
Rajasekhar Amudala
Email: br8dba@gmail.com
Linkedin: https://www.linkedin.com/in/rajasekhar-amudala/

PostgreSQL Backup and Restore Using pg_dumpall

PostgreSQL, , , , , , , , , , , , , , , , , , , , , , ,

PostgreSQL Backup and Restore Using pg_dumpall and psql

Table of Contents

0. Introduction

Backup:

1. Backup All Databases
2. Backup Users/Roles Definition
3. Backup Tablespaces Definition
4. Backup Schema Only (No Data)
5. Backup Data Only (No Schema)
6. Backup Data as INSERT Commands
7. Backup Global Objects Only (No Databases)

Restore:

8. Restore on Same Host

9. Restore to Another Host (Different Tablespace Paths)

Click to expand pg_dumpall –help
[postgres@lxtrdpgdsgv01 ~]$ pg_dumpall --help
pg_dumpall extracts a PostgreSQL database cluster into an SQL script file.

Usage:
  pg_dumpall [OPTION]...

General options:
  -f, --file=FILENAME          output file name
  -v, --verbose                verbose mode
  -V, --version                output version information, then exit
  --lock-wait-timeout=TIMEOUT  fail after waiting TIMEOUT for a table lock
  -?, --help                   show this help, then exit

Options controlling the output content:
  -a, --data-only              dump only the data, not the schema
  -c, --clean                  clean (drop) databases before recreating
  -E, --encoding=ENCODING      dump the data in encoding ENCODING
  -g, --globals-only           dump only global objects, no databases
  -O, --no-owner               skip restoration of object ownership
  -r, --roles-only             dump only roles, no databases or tablespaces
  -s, --schema-only            dump only the schema, no data
  -S, --superuser=NAME         superuser user name to use in the dump
  -t, --tablespaces-only       dump only tablespaces, no databases or roles
  -x, --no-privileges          do not dump privileges (grant/revoke)
  --binary-upgrade             for use by upgrade utilities only
  --column-inserts             dump data as INSERT commands with column names
  --disable-dollar-quoting     disable dollar quoting, use SQL standard quoting
  --disable-triggers           disable triggers during data-only restore
  --exclude-database=PATTERN   exclude databases whose name matches PATTERN
  --extra-float-digits=NUM     override default setting for extra_float_digits
  --if-exists                  use IF EXISTS when dropping objects
  --inserts                    dump data as INSERT commands, rather than COPY
  --load-via-partition-root    load partitions via the root table
  --no-comments                do not dump comments
  --no-publications            do not dump publications
  --no-role-passwords          do not dump passwords for roles
  --no-security-labels         do not dump security label assignments
  --no-subscriptions           do not dump subscriptions
  --no-sync                    do not wait for changes to be written safely to disk
  --no-table-access-method     do not dump table access methods
  --no-tablespaces             do not dump tablespace assignments
  --no-toast-compression       do not dump TOAST compression methods
  --no-unlogged-table-data     do not dump unlogged table data
  --on-conflict-do-nothing     add ON CONFLICT DO NOTHING to INSERT commands
  --quote-all-identifiers      quote all identifiers, even if not key words
  --restrict-key=RESTRICT_KEY  use provided string as psql \restrict key
  --rows-per-insert=NROWS      number of rows per INSERT; implies --inserts
  --use-set-session-authorization
                               use SET SESSION AUTHORIZATION commands instead of
                               ALTER OWNER commands to set ownership

Connection options:
  -d, --dbname=CONNSTR     connect using connection string
  -h, --host=HOSTNAME      database server host or socket directory
  -l, --database=DBNAME    alternative default database
  -p, --port=PORT          database server port number
  -U, --username=NAME      connect as specified database user
  -w, --no-password        never prompt for password
  -W, --password           force password prompt (should happen automatically)
  --role=ROLENAME          do SET ROLE before dump

If -f/--file is not used, then the SQL script will be written to the standard
output.

Report bugs to <pgsql-bugs@lists.postgresql.org>.
PostgreSQL home page: <https://www.postgresql.org/>
[postgres@lxtrdpgdsgv01 ~]$

 

0. Introduction

Note: pg_dumpall does not support custom format backups.

The pg_dumpall utility is used to back up an entire PostgreSQL environment, including:

* Roles and users
* Tablespaces
* All databases (schemas and data)

It is especially useful for:

* Full cluster migrations
* Disaster recovery
* Environment replication across dev, QA, and prod

When restoring to a different host, you'll need to:

* Update tablespace paths (using tools like sed)
* Pre-create required tablespace directories

This ensures compatibility and successful restoration across different environments.

Backup


1. Backup ALL databases

[postgres@lxtrdpgdsgv01 ~]$ nohup pg_dumpall -U postgres -v -f /pgBackup/pgsql15/backup/backup_all_databases_10OCT2025.sql > /pgBackup/pgsql15/backup/backup_all_databases_10OCT2025.log 2>&1 &
[1] 5610
[postgres@lxtrdpgdsgv01 ~]$ 
[postgres@lxtrdpgdsgv01 ~]$ cat /pgBackup/pgsql15/backup/backup_all_databases_10OCT2025.log | grep -i /pgBackup/pgsql15/backup/backup_all_databases_10OCT2025.sql
pg_dumpall: running ""/usr/pgsql-15/bin/pg_dump"  -v -f /pgBackup/pgsql15/backup/backup_all_databases_10OCT2025.sql  -Fa 'user=postgres dbname=template1'"
pg_dumpall: running ""/usr/pgsql-15/bin/pg_dump"  -v -f /pgBackup/pgsql15/backup/backup_all_databases_10OCT2025.sql --create -Fa 'user=postgres dbname=edpua'"
pg_dumpall: running ""/usr/pgsql-15/bin/pg_dump"  -v -f /pgBackup/pgsql15/backup/backup_all_databases_10OCT2025.sql --create -Fa 'user=postgres dbname=gebua'"
pg_dumpall: running ""/usr/pgsql-15/bin/pg_dump"  -v -f /pgBackup/pgsql15/backup/backup_all_databases_10OCT2025.sql --create -Fa 'user=postgres dbname=orcl'"
pg_dumpall: running ""/usr/pgsql-15/bin/pg_dump"  -v -f /pgBackup/pgsql15/backup/backup_all_databases_10OCT2025.sql  -Fa 'user=postgres dbname=postgres'"
[postgres@lxtrdpgdsgv01 ~]$

[postgres@lxtrdpgdsgv01 ~]$ psql
psql (15.14)
Type "help" for help.

postgres=# \c orcl
You are now connected to database "orcl" as user "postgres".
orcl=# SELECT
orcl-#     schemaname || '.' || relname AS table_name,
orcl-#     pg_size_pretty(pg_total_relation_size(relid)) AS total_size,
orcl-#     pg_size_pretty(pg_relation_size(relid)) AS table_size,
orcl-#     pg_size_pretty(pg_total_relation_size(relid) - pg_relation_size(relid)) AS index_size
orcl-# FROM
orcl-#     pg_catalog.pg_statio_user_tables
orcl-# ORDER BY
orcl-#     pg_total_relation_size(relid) DESC;
    table_name    | total_size | table_size | index_size
------------------+------------+------------+------------
 trd.metrics_high | 799 MB     | 498 MB     | 301 MB
 trd.metrics_mid  | 638 MB     | 398 MB     | 240 MB
 trd.employees    | 493 MB     | 322 MB     | 172 MB
 trd.sales_2023   | 399 MB     | 249 MB     | 150 MB
 trd.sales_2024   | 399 MB     | 249 MB     | 150 MB
 trd.sales_2022   | 399 MB     | 249 MB     | 150 MB
 trd.sales_2021   | 398 MB     | 248 MB     | 150 MB
 trd.metrics_low  | 159 MB     | 99 MB      | 60 MB
 trd.test_data    | 71 MB      | 50 MB      | 21 MB
 trd.emp_summary  | 24 kB      | 8192 bytes | 16 kB
 trd.metrics_rest | 8192 bytes | 0 bytes    | 8192 bytes
(11 rows)

orcl=#


2. Backup users/roles definition

[postgres@lxtrdpgdsgv01 ~]$ nohup pg_dumpall -U postgres --roles-only -v -f /pgBackup/pgsql15/backup/roles.sql > /pgBackup/pgsql15/backup/roles.log 2>&1 &
[1] 5205
[postgres@lxtrdpgdsgv01 ~]$


3. Backup tablespaces definition

[postgres@lxtrdpgdsgv01 ~]$ nohup pg_dumpall -U postgres --tablespaces-only -v -f /pgBackup/pgsql15/backup/tablespaces.sql > /pgBackup/pgsql15/backup/tablespaces.log 2>&1 &
[1] 5183
[postgres@lxtrdpgdsgv01 ~]$


4. Backup dump only the schema, no data

[postgres@lxtrdpgdsgv01 ~]$ nohup pg_dumpall -U postgres --schema-only -v -f /pgBackup/pgsql15/backup/schemas.sql > /pgBackup/pgsql15/backup/schemas.log 2>&1 &
[1] 4890
[postgres@lxtrdpgdsgv01 ~]$


5. Backup dump only the data, not the schema

[postgres@lxtrdpgdsgv01 ~]$ nohup pg_dumpall -U postgres --data-only -v -f /pgBackup/pgsql15/backup/dataonly.sql > /pgBackup/pgsql15/backup/dataonly.log 2>&1 &
[1] 5233
[postgres@lxtrdpgdsgv01 ~]$


6. Backup dump data as INSERT commands, rather than COPY

[postgres@lxtrdpgdsgv01 ~]$ nohup pg_dumpall -U postgres --inserts -v -f /pgBackup/pgsql15/backup/inserts.sql > /pgBackup/pgsql15/backup/inserts.log 2>&1 &
[1] 5274
[postgres@lxtrdpgdsgv01 ~]$


7. Backup dump only global objects, no databases

[postgres@lxtrdpgdsgv01 ~]$ nohup pg_dumpall -U postgres --globals-only -v -f /pgBackup/pgsql15/backup/globals.sql > /pgBackup/pgsql15/backup/globals.log 2>&1 &
[1] 5331
[postgres@lxtrdpgdsgv01 ~]$

Restore


8. Restore on same host


A. Drop Existing Databases (Optional)

 

[postgres@lxtrdpgdsgv01 ~]$ psql
psql (15.14)
Type "help" for help.

postgres=# \l
                                                 List of databases
   Name    |  Owner   | Encoding |   Collate   |    Ctype    | ICU Locale | Locale Provider |   Access privileges
-----------+----------+----------+-------------+-------------+------------+-----------------+-----------------------
 edpua     | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |            | libc            |
 gebua     | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |            | libc            |
 orcl      | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |            | libc            |
 postgres  | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |            | libc            |
 template0 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |            | libc            | =c/postgres          +
           |          |          |             |             |            |                 | postgres=CTc/postgres
 template1 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |            | libc            | postgres=CTc/postgres+
           |          |          |             |             |            |                 | =c/postgres
(6 rows)

postgres=# drop database edpua;
DROP DATABASE
postgres=# drop database gebua;
DROP DATABASE
postgres=# drop database orcl;
DROP DATABASE
postgres=# \l
                                                 List of databases
   Name    |  Owner   | Encoding |   Collate   |    Ctype    | ICU Locale | Locale Provider |   Access privileges
-----------+----------+----------+-------------+-------------+------------+-----------------+-----------------------
 postgres  | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |            | libc            |
 template0 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |            | libc            | =c/postgres          +
           |          |          |             |             |            |                 | postgres=CTc/postgres
 template1 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |            | libc            | postgres=CTc/postgres+
           |          |          |             |             |            |                 | =c/postgres
(3 rows)

postgres=#

postgres=# \db
             List of tablespaces
    Name    |  Owner   |      Location
------------+----------+---------------------
 edpua_ix   | postgres | /pgIx/pgsql15/edpua
 edpua_tb   | postgres | /pgTb/pgsql15/edpua
 gebua_ix   | postgres | /pgIx/pgsql15/gebua
 gebua_tb   | postgres | /pgTb/pgsql15/gebua
 orcl_ix    | postgres | /pgIx/pgsql15/orcl
 orcl_tb    | postgres | /pgTb/pgsql15/orcl
 pg_default | postgres |
 pg_global  | postgres |
(8 rows)

postgres=#


B. Restore Full Backup

[postgres@lxtrdpgdsgv01 ~]$ nohup psql -U postgres -X -f /pgBackup/pgsql15/backup/backup_all_databases_10OCT2025.sql -d postgres > /pgBackup/pgsql15/backup/backup_all_databases_10OCT2025_restore.log
[1] 4132
[postgres@lxtrdpgdsgv01 ~]$ 

-- OR --

nohup psql -U postgres -f /pgBackup/pgsql15/backup/backup_all_databases_10OCT2025.sql > /pgBackup/pgsql15/backup/backup_all_databases_10OCT2025_restore.log 2>&1 &

-- Log: backup_all_databases_10OCT2025_restore.log


C. Verification

[postgres@lxtrdpgdsgv01 ~]$ psql
psql (15.14)
Type "help" for help.

postgres=# \l
                                                 List of databases
   Name    |  Owner   | Encoding |   Collate   |    Ctype    | ICU Locale | Locale Provider |   Access privileges
-----------+----------+----------+-------------+-------------+------------+-----------------+-----------------------
 edpua     | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |            | libc            |
 gebua     | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |            | libc            |
 orcl      | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |            | libc            |
 postgres  | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |            | libc            |
 template0 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |            | libc            | =c/postgres          +
           |          |          |             |             |            |                 | postgres=CTc/postgres
 template1 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |            | libc            | postgres=CTc/postgres+
           |          |          |             |             |            |                 | =c/postgres
(6 rows)

postgres=#


9. Restore to Another Host (Different Tablespace Paths)

A. Copy Backup File

[postgres@lxtrdpgdsgv01 backup]$ scp backup_all_databases_10OCT2025.sql 192.168.2.31:/pgBackup/pgsql15/backup/
postgres@192.168.2.31's password:
backup_all_databases_10OCT2025.sql                 100% 3556MB  51.5MB/s   01:09
[postgres@lxtrdpgdsgv01 backup]$ 

[postgres@pg17 backup]$ ls -ltr backup_all_databases_10OCT2025.sql
-rw-r--r--. 1 postgres postgres 3729147646 Oct  6 06:17 backup_all_databases_10OCT2025.sql
[postgres@pg17 backup]$


B. Extract Tablespace/Database Info

[postgres@lxtrdpgdsgv01 backup]$ grep -i "CREATE TABLESPACE" /pgBackup/pgsql15/backup/backup_all_databases_10OCT2025.sql
CREATE TABLESPACE orcl_tb OWNER postgres LOCATION '/pgTb/pgsql15/orcl';
CREATE TABLESPACE orcl_ix OWNER postgres LOCATION '/pgIx/pgsql15/orcl';
CREATE TABLESPACE gebua_tb OWNER postgres LOCATION '/pgTb/pgsql15/gebua';
CREATE TABLESPACE gebua_ix OWNER postgres LOCATION '/pgIx/pgsql15/gebua';
CREATE TABLESPACE edpua_tb OWNER postgres LOCATION '/pgTb/pgsql15/edpua';
CREATE TABLESPACE edpua_ix OWNER postgres LOCATION '/pgIx/pgsql15/edpua';
[postgres@lxtrdpgdsgv01 backup]$
[postgres@lxtrdpgdsgv01 backup]$ grep -i "CREATE DATABASE" /pgBackup/pgsql15/backup/backup_all_databases_10OCT2025.sql
CREATE DATABASE edpua WITH TEMPLATE = template0 ENCODING = 'UTF8' LOCALE_PROVIDER = libc LOCALE = 'en_US.UTF-8' TABLESPACE = edpua_tb;
CREATE DATABASE gebua WITH TEMPLATE = template0 ENCODING = 'UTF8' LOCALE_PROVIDER = libc LOCALE = 'en_US.UTF-8' TABLESPACE = gebua_tb;
CREATE DATABASE orcl WITH TEMPLATE = template0 ENCODING = 'UTF8' LOCALE_PROVIDER = libc LOCALE = 'en_US.UTF-8' TABLESPACE = orcl_tb;
[postgres@lxtrdpgdsgv01 backup]$


C. Create Tablespace Directories on Target

[postgres@pg17 ~]$ psql
psql (15.13)
Type "help" for help.

postgres=# \l
                                                 List of databases
   Name    |  Owner   | Encoding |   Collate   |    Ctype    | ICU Locale | Locale Provider |   Access privileges
-----------+----------+----------+-------------+-------------+------------+-----------------+-----------------------
 postgres  | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |            | libc            |
 template0 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |            | libc            | =c/postgres          +
           |          |          |             |             |            |                 | postgres=CTc/postgres
 template1 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |            | libc            | postgres=CTc/postgres+
           |          |          |             |             |            |                 | =c/postgres
(3 rows)

postgres=#
postgres=# \db
       List of tablespaces
    Name    |  Owner   | Location
------------+----------+----------
 pg_default | postgres |
 pg_global  | postgres |
(2 rows)

postgres=#


# Create Directory 

[postgres@pg17 ~]$ mkdir -p /pgData/pgsql15/orcl_tb
[postgres@pg17 ~]$ mkdir -p /pgData/pgsql15/orcl_ix
[postgres@pg17 ~]$ mkdir -p /pgData/pgsql15/gebua_tb
[postgres@pg17 ~]$ mkdir -p /pgData/pgsql15/gebua_ix
[postgres@pg17 ~]$ mkdir -p /pgData/pgsql15/edpua_tb
[postgres@pg17 ~]$ mkdir -p /pgData/pgsql15/edpua_ix


D. Create Tablespaces in PostgreSQL

postgres=# CREATE TABLESPACE orcl_tb OWNER postgres LOCATION  '/pgData/pgsql15/orcl_tb';
CREATE TABLESPACE
postgres=# CREATE TABLESPACE orcl_ix OWNER postgres LOCATION  '/pgData/pgsql15/orcl_ix';
CREATE TABLESPACE
postgres=# CREATE TABLESPACE gebua_tb OWNER postgres LOCATION '/pgData/pgsql15/gebua_tb';
CREATE TABLESPACE
postgres=# CREATE TABLESPACE gebua_ix OWNER postgres LOCATION '/pgData/pgsql15/gebua_ix';
CREATE TABLESPACE
postgres=# CREATE TABLESPACE edpua_tb OWNER postgres LOCATION '/pgData/pgsql15/edpua_tb';
CREATE TABLESPACE
postgres=# CREATE TABLESPACE edpua_ix OWNER postgres LOCATION '/pgData/pgsql15/edpua_ix';
CREATE TABLESPACE
postgres=#


-- OR --- 
 You can modify the tablespace paths directly in the backup file; however, this approach is not recommended for large backup files due to  reliability concerns.

cd /pgBackup/pgsql15/backup/
# Replace ORCL paths
sed -i 's|/pgTb/pgsql15/orcl|/pgData/pgsql15/orcl_tb|g' backup_all_databases_10OCT2025.sql
sed -i 's|/pgIx/pgsql15/orcl|/pgData/pgsql15/orcl_ix|g' backup_all_databases_10OCT2025.sql

# Replace GEBUA paths
sed -i 's|/pgTb/pgsql15/gebua|/pgData/pgsql15/gebua_tb|g' backup_all_databases_10OCT2025.sql
sed -i 's|/pgIx/pgsql15/gebua|/pgData/pgsql15/gebua_ix|g' backup_all_databases_10OCT2025.sql

# Replace EDPUA paths
sed -i 's|/pgTb/pgsql15/edpua|/pgData/pgsql15/edpua_tb|g' backup_all_databases_10OCT2025.sql
sed -i 's|/pgIx/pgsql15/edpua|/pgData/pgsql15/edpua_ix|g' backup_all_databases_10OCT2025.sql


[postgres@pg17 ~]$ psql
psql (15.13)
Type "help" for help.

postgres=# \db
               List of tablespaces
    Name    |  Owner   |         Location
------------+----------+--------------------------
 edpua_ix   | postgres | /pgData/pgsql15/edpua_ix
 edpua_tb   | postgres | /pgData/pgsql15/edpua_tb
 gebua_ix   | postgres | /pgData/pgsql15/gebua_ix
 gebua_tb   | postgres | /pgData/pgsql15/gebua_tb
 orcl_ix    | postgres | /pgData/pgsql15/orcl_ix
 orcl_tb    | postgres | /pgData/pgsql15/orcl_tb
 pg_default | postgres |
 pg_global  | postgres |
(8 rows)

postgres=#


E. Optional: Backup on Target Host

[postgres@pg17 ~]$ nohup pg_dumpall -U postgres -v -f /pgBackup/pgsql15/backup/backup_all_databases_10OCT2025_pg17.sql > /pgBackup/pgsql15/backup/backup_all_databases_10OCT2025_pg17.log 2>&1 &
[1] 4246
[postgres@pg17 ~]$


F. Restore on Target Host

[postgres@pg17 ~]$ nohup psql -U postgres -X -f /pgBackup/pgsql15/backup/backup_all_databases_10OCT2025.sql -d postgres > /pgBackup/pgsql15/backup/backup_all_databases_10OCT2025_restore_pg17.log 2>&1 &
[1] 5213
[postgres@pg17 ~]$ 

-- OR --

nohup psql -U postgres -f /pgBackup/pgsql15/backup/backup_all_databases_10OCT2025.sql > /pgBackup/pgsql15/backup/backup_all_databases_10OCT2025_restore_pg17.log 2>&1 &

-- Log: backup_all_databases_10OCT2025_restore_pg17.log


G. Final Verification

[postgres@pg17 ~]$ psql
psql (15.13)
Type "help" for help.

postgres=# \l
List of databases
Name | Owner | Encoding | Collate | Ctype | ICU Locale | Locale Provider | Access privileges
-----------+----------+----------+-------------+-------------+------------+-----------------+-----------------------
 edpua | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | | libc |
gebua | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | | libc |
orcl | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | | libc |
postgres | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | | libc |
template0 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | | libc | =c/postgres +
| | | | | | | postgres=CTc/postgres
template1 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | | libc | postgres=CTc/postgres+
| | | | | | | =c/postgres
(6 rows)

postgres=#

[postgres@pg17 ~]$ psql
psql (15.13)
Type "help" for help.

postgres=# \c orcl
You are now connected to database "orcl" as user "postgres".
orcl=# SELECT
orcl-# schemaname || '.' || relname AS table_name,
orcl-# pg_size_pretty(pg_total_relation_size(relid)) AS total_size,
orcl-# pg_size_pretty(pg_relation_size(relid)) AS table_size,
orcl-# pg_size_pretty(pg_total_relation_size(relid) - pg_relation_size(relid)) AS index_size
orcl-# FROM
orcl-# pg_catalog.pg_statio_user_tables
orcl-# ORDER BY
orcl-# pg_total_relation_size(relid) DESC;
 table_name | total_size | table_size | index_size
------------------+------------+------------+------------
trd.metrics_high | 799 MB | 498 MB | 301 MB
trd.metrics_mid | 638 MB | 398 MB | 240 MB
trd.employees | 493 MB | 322 MB | 172 MB
trd.sales_2023 | 399 MB | 249 MB | 150 MB
trd.sales_2024 | 399 MB | 249 MB | 150 MB
trd.sales_2022 | 399 MB | 249 MB | 150 MB
trd.sales_2021 | 398 MB | 248 MB | 150 MB
trd.metrics_low | 159 MB | 99 MB | 60 MB
trd.test_data | 71 MB | 50 MB | 21 MB
trd.emp_summary | 24 kB | 8192 bytes | 16 kB
trd.metrics_rest | 8192 bytes | 0 bytes | 8192 bytes
(11 rows)

orcl=#

Caution: Your use of any information or materials on this website is entirely at your own risk. It is provided for educational purposes only. It has been tested internally, however, we do not guarantee that it will work for you. Ensure that you run it in your test environment before using.

Thank you,
Rajasekhar Amudala
Email: br8dba@gmail.com
Linkedin: https://www.linkedin.com/in/rajasekhar-amudala/