Review my steps for rollback to restore point

On Tue, 2025-03-04 at 14:26 +0530, chandan Kumar wrote:

Hello,
 I hope you are doing fine. I need your expertise on below case study.
My current production environment is 2 node streaming replication hosted on
Ubuntu VM 's on Azure. I have performed below steps on primary database.
1- Take Base backup
2-  Create a restore point using pg_create_restore_point()
3-  executed some DDL statement (CREATE VIEW,ADD INDEX,DROP INDEX)
4-  Perform rollback using restore point
 To rollback, you must stop PostgreSQL, restore the last full backup, and apply
WAL files until the restore point:
1. Stop PostgreSQL Service
2. Restore from Full Backup (Using pg_basebackup)
3. Modify recovery.conf (or postgresql.conf for newer versions)
o Set recovery target name:
                                              recovery_target_name = 'before_ddl_changes'
                                              recovery_target_action = 'pause'
o Set restore_command to replay WAL logs:
                                             restore_command = 'cp /path/to/wal_archive/%f %p'
4. Start PostgreSQL
                 sudo systemctl start postgresql
5. Verify Recovery Status
                SELECT pg_is_in_recovery();
                After verification, finalize recovery:
                touch /var/lib/postgresql/data/recovery.signal
                or
                rm /var/lib/postgresql/data/recovery.conf
               Then restart PostgreSQL.
6. Reestablish replication 

Could you please help if my steps are correct ? Can we achieve rollback from any
other approach without restoring basebackup?

You have to create /var/lib/postgresql/data/recovery.signal *before* you
start the server. Forget about "recovery.conf", that was before v12.

You can set "recovery_target_action = 'promote'".

Yours,
Laurenz Albe

Thank you for your answer. I want to clarify one more doubt. Can PITR be
achieved without applying Base Backup

On Tue, Mar 4, 2025 at 3:12 PM Laurenz Albe <laurenz.albe@cybertec.at>
wrote:

On Tue, 2025-03-04 at 14:26 +0530, chandan Kumar wrote:

Hello,
I hope you are doing fine. I need your expertise on below case study.
My current production environment is 2 node streaming replication hosted

on

Ubuntu VM 's on Azure. I have performed below steps on primary database.
1- Take Base backup
2- Create a restore point using pg_create_restore_point()
3- executed some DDL statement (CREATE VIEW,ADD INDEX,DROP INDEX)
4- Perform rollback using restore point
To rollback, you must stop PostgreSQL, restore the last full backup,

and apply

WAL files until the restore point:
1. Stop PostgreSQL Service
2. Restore from Full Backup (Using pg_basebackup)
3. Modify recovery.conf (or postgresql.conf for newer versions)
o Set recovery target name:
recovery_target_name =

'before_ddl_changes'

recovery_target_action =

'pause'

o Set restore_command to replay WAL logs:
restore_command = 'cp

/path/to/wal_archive/%f %p'

4. Start PostgreSQL
sudo systemctl start postgresql
5. Verify Recovery Status
SELECT pg_is_in_recovery();
After verification, finalize recovery:
touch /var/lib/postgresql/data/recovery.signal
or
rm /var/lib/postgresql/data/recovery.conf
Then restart PostgreSQL.
6. Reestablish replication

Could you please help if my steps are correct ? Can we achieve rollback

from any

other approach without restoring basebackup?

You have to create /var/lib/postgresql/data/recovery.signal *before* you
start the server. Forget about "recovery.conf", that was before v12.

You can set "recovery_target_action = 'promote'".

Yours,
Laurenz Albe

--
*With warm regards*
* Chandan*

On Tuesday, March 4, 2025, chandan Kumar <chandan.issyoga@gmail.com> wrote:

Thank you for your answer. I want to clarify one more doubt. Can PITR be
achieved without applying Base Backup

The point-in-time you choose must be in the future relative to whatever
data files you are applying WAL on top of. That is only possible of you’ve
backed up the data files at some point in the past and use that backup.

David J.

Thank you for your time and clarification.
Does PITR recreate database internally ? can i say it is not the same as
pg_restore or it is same as pg_restore plus applying WAL on top of it. I
am asking because can we revern DDL operations without PITR in streaming
replication

On Tue, Mar 4, 2025 at 8:37 PM David G. Johnston <david.g.johnston@gmail.com>
wrote:

On Tuesday, March 4, 2025, chandan Kumar <chandan.issyoga@gmail.com>
wrote:

Thank you for your answer. I want to clarify one more doubt. Can PITR
be achieved without applying Base Backup

The point-in-time you choose must be in the future relative to whatever
data files you are applying WAL on top of. That is only possible of you’ve
backed up the data files at some point in the past and use that backup.

David J.

--
*With warm regards*
* Chandan*

Chandran,

1. For PITR, you should use a tool like PgBackRest. It handles all
$PGDATA and WAL archiving. It's multithreaded, too,
2. pg_restore is just for logical backups.
3. Streaming Replication is for *hot standby*, not backups.

On Tue, Mar 4, 2025 at 10:00 AM chandan Kumar <chandan.issyoga@gmail.com>
wrote:

Thank you for your answer. I want to clarify one more doubt. Can PITR be
achieved without applying Base Backup

On Tue, Mar 4, 2025 at 3:12 PM Laurenz Albe <laurenz.albe@cybertec.at>
wrote:

On Tue, 2025-03-04 at 14:26 +0530, chandan Kumar wrote:

Hello,
I hope you are doing fine. I need your expertise on below case study.
My current production environment is 2 node streaming replication

hosted on

Ubuntu VM 's on Azure. I have performed below steps on primary database.
1- Take Base backup
2- Create a restore point using pg_create_restore_point()
3- executed some DDL statement (CREATE VIEW,ADD INDEX,DROP INDEX)
4- Perform rollback using restore point
To rollback, you must stop PostgreSQL, restore the last full backup,

and apply

WAL files until the restore point:
1. Stop PostgreSQL Service
2. Restore from Full Backup (Using pg_basebackup)

[snip]

--
Death to <Redacted>, and butter sauce.
Don't boil me, I'm still alive.
<Redacted> lobster!

On Tuesday, March 4, 2025, chandan Kumar <chandan.issyoga@gmail.com> wrote:

Thank you for your time and clarification.
Does PITR recreate database internally ? can i say it is not the same as
pg_restore or it is same as pg_restore plus applying WAL on top of it. I
am asking because can we revern DDL operations without PITR in streaming
replication

PostgreSQL doesn’t have a concept of “revert”.

PITR just deals with raw bytes on disk for an entire cluster. If a new
file appears in the WAL that file is created. That file can be a directory
for a database.

You cannot mix physical and logical images of the database so applying WAL
on top of pg_restore is technically invalid - but it does effective convey
the idea. It’s like saying pg_dump and pg_basebackup are similar. Sure,
in some ways that is true - but the logical vs. physical distinction cannot
be ignored fully.

David J.

Thank you !

On Tue, Mar 4, 2025 at 9:08 PM Ron Johnson <ronljohnsonjr@gmail.com> wrote:

Chandran,

1. For PITR, you should use a tool like PgBackRest. It handles all
$PGDATA and WAL archiving. It's multithreaded, too,
2. pg_restore is just for logical backups.
3. Streaming Replication is for *hot standby*, not backups.

On Tue, Mar 4, 2025 at 10:00 AM chandan Kumar <chandan.issyoga@gmail.com>
wrote:

Thank you for your answer. I want to clarify one more doubt. Can PITR
be achieved without applying Base Backup

On Tue, Mar 4, 2025 at 3:12 PM Laurenz Albe <laurenz.albe@cybertec.at>
wrote:

On Tue, 2025-03-04 at 14:26 +0530, chandan Kumar wrote:

Hello,
I hope you are doing fine. I need your expertise on below case study.
My current production environment is 2 node streaming replication

hosted on

Ubuntu VM 's on Azure. I have performed below steps on primary

database.

1- Take Base backup
2- Create a restore point using pg_create_restore_point()
3- executed some DDL statement (CREATE VIEW,ADD INDEX,DROP INDEX)
4- Perform rollback using restore point
To rollback, you must stop PostgreSQL, restore the last full backup,

and apply

WAL files until the restore point:
1. Stop PostgreSQL Service
2. Restore from Full Backup (Using pg_basebackup)

[snip]

--
Death to <Redacted>, and butter sauce.
Don't boil me, I'm still alive.
<Redacted> lobster!

--
*With warm regards*
* Chandan*

Hi David,
You catched my word "revert". Thats so encouraging to see how this
community helps. Your answer has cleared my 99% doubt. Thanks again.
I wish I also contribute one day . Have a good time!

On Tue, Mar 4, 2025 at 9:08 PM David G. Johnston <david.g.johnston@gmail.com>
wrote:

On Tuesday, March 4, 2025, chandan Kumar <chandan.issyoga@gmail.com>
wrote:

Thank you for your time and clarification.
Does PITR recreate database internally ? can i say it is not the same as
pg_restore or it is same as pg_restore plus applying WAL on top of it. I
am asking because can we revern DDL operations without PITR in streaming
replication

PostgreSQL doesn’t have a concept of “revert”.

PITR just deals with raw bytes on disk for an entire cluster. If a new
file appears in the WAL that file is created. That file can be a directory
for a database.

You cannot mix physical and logical images of the database so applying WAL
on top of pg_restore is technically invalid - but it does effective convey
the idea. It’s like saying pg_dump and pg_basebackup are similar. Sure,
in some ways that is true - but the logical vs. physical distinction cannot
be ignored fully.

David J.

--
*With warm regards*
* Chandan*

Dear Team,
Thank you for all the responses I have received in this matter. I would
like to send my final steps that I am going to follow during PITR.
kindly take some out to see if these steps are correct or need any
correction or advise.

*Performing Database rollback using PITR*

*Steps: *

*Pre requisites*

1) Ensure WAL Archiving is Enabled

2) Ensure postgres have access to write WAL Files on archive location

3) Check WAL files are being generated in default directory

4) Check WAL files are being archived in archive directory

5) Ensure Replication is Running fine, check if any lag

6) Backup PostgreSQL config files (postgres.conf, hba, repmgr config
file)

*Implementation steps:*

1. Take a Base Backup (Before Making Any Changes)

2. Create a restore point

*SELECT pg_create_restore_point('before_database_update');*

3. Execute DDL statements

4. Validate changes

If the changes are *not* as expected, proceed to rollback (PITR).

5. Unregister the standby first

*repmgr -f /etc/postgresql/14/main/repmgr.conf standby unregister*

6. Stop both servers (Primary & Standby)

*sudo systemctl stop postgresql@14-main*

7. Move the Old Data Directory (Backup Just in Case)

* mv /var/lib/postgresql/14/main
/var/lib/postgresql/14/main_old_$(date +%F)*

8. Extract the Base Backup to the Data Directory

9. make sure Correct Ownership is granted to user postgres to
data directory

10. Create the recovery.signal File

*touch /var/lib/postgresql/14/main/recovery.signal*

11. Update postgresql.auto.conf

*echo "restore_command = 'cp /var/lib/postgresql/wal_archive/%f %p'" >>
/var/lib/postgresql/14/main/postgresql.auto.conf*

*echo "recovery_target_name = 'before_database_update'" >>
/var/lib/postgresql/14/main/postgresql.auto.conf*

*echo "recovery_target_action = 'promote'" >>
/var/lib/postgresql/14/main/postgresql.auto.conf*

8 Start PostgreSQL on primary (rollback is done)

*sudo systemctl start postgresql@14-main*

9 Verify recovery status

*psql -U postgres -c "SELECT pg_is_in_recovery();"*

10 Reestablish replication- Standby needs to rebuilt to match
primary after PITR.

11 Create the replication slot on primary, it might gets deleted
during PITR

* select * from
pg_create_physical_replication_slot('node_a_repslot');*

12. Move/rename standby signal , because standby signal will be
created in next step

*mv standby.signal standbyold.signal*

13. Start Standby

14. Register the standby

15. Check Replication Status

On Tue, Mar 4, 2025 at 9:15 PM chandan Kumar <chandan.issyoga@gmail.com>
wrote:

Hi David,
You catched my word "revert". Thats so encouraging to see how this
community helps. Your answer has cleared my 99% doubt. Thanks again.
I wish I also contribute one day . Have a good time!

On Tue, Mar 4, 2025 at 9:08 PM David G. Johnston <
david.g.johnston@gmail.com> wrote:

On Tuesday, March 4, 2025, chandan Kumar <chandan.issyoga@gmail.com>
wrote:

Thank you for your time and clarification.
Does PITR recreate database internally ? can i say it is not the same
as pg_restore or it is same as pg_restore plus applying WAL on top of it.
I am asking because can we revern DDL operations without PITR in streaming
replication

PostgreSQL doesn’t have a concept of “revert”.

PITR just deals with raw bytes on disk for an entire cluster. If a new
file appears in the WAL that file is created. That file can be a directory
for a database.

You cannot mix physical and logical images of the database so applying
WAL on top of pg_restore is technically invalid - but it does effective
convey the idea. It’s like saying pg_dump and pg_basebackup are similar.
Sure, in some ways that is true - but the logical vs. physical distinction
cannot be ignored fully.

David J.

--
*With warm regards*
* Chandan*

--
*With warm regards*
* Chandan*

On Thu, Mar 6, 2025 at 6:49 AM chandan Kumar <chandan.issyoga@gmail.com>
wrote:

need any correction or advise.

Honestly, this all seems overly complex and fragile. I'm not sure what the
overall goal is, but if it's to have a general PITR solution, use
pgBackRest. If it's just to have a fall back method for a particular
change, an easier solution is to stop replication, apply changes, and
promote the replica if something goes wrong.

Either way, you should have a test system setup that you can try out your
steps on. If a step fails and you do not understand why, this list is a
great resource. Practice this a lot on test systems until it all becomes
second nature.

Cheers,
Greg

--
Crunchy Data - https://www.crunchydata.com
Enterprise Postgres Software Products & Tech Support