Re: [Patch] pg_rewind: options to use restore_command fromrecovery.conf or command line

On 01.12.2019 5:57, Michael Paquier wrote:
> On Thu, Sep 26, 2019 at 03:08:22PM +0300, Alexey Kondratov wrote:
>> As Alvaro correctly pointed in the nearby thread [1], we've got an
>> interference regarding -R command line argument. I agree that it's a good
>> idea to reserve -R for recovery configuration write to be consistent with
>> pg_basebackup, so I've updated my patch to use another letters:
> The patch has rotten and does not apply anymore.  Could you please
> send a rebased version?  I have moved the patch to next CF, waiting on
> author for now.

Rebased and updated patch is attached.

There was a problem with testing new restore_command options altogether 
with recent ensureCleanShutdown. My test simply moves all WAL from 
pg_wal and generates restore_command for a new options testing, but this 
prevents startup recovery required by ensureCleanShutdown. To test both 
options in the same we have to leave some recent WAL segments in the 
pg_wal and be sure that they are enough for startup recovery, but not 
enough for successful pg_rewind run. I have manually figured out that 
required amount of inserted records (and generated WAL) to achieve this. 
However, I think that this approach is not good for test, since tests 
may be modified in the future (amount of writes to DB changed) or even 
volume of WAL written by Postgres will change. It will lead to falsely 
always failed or passed tests.

Moreover, testing both ensureCleanShutdown and new options in the same 
time doesn't hit new code paths, so I decided to test new options with 
--no-ensure-shutdown for simplicity and stability of tests.


Regards

-- 
Alexey Kondratov

Postgres Professional https://www.postgrespro.com
Russian Postgres Company