Re: strange behavior of WAL files

I will try to simulate this and see if i can reproduce it, currently in
between difficult interviews where i have little hope :)

PostgreSQL WAL Retention and Clean Up: pg_archivecleanup - Percona Database
Performance Blog
<https://www.percona.com/blog/2019/07/10/wal-retention-and-clean-up-pg_archivecleanup/>
WAL, LSN and File Names – Luca Ferrari – Open Source advocate, human being
(fluca1978.github.io)
<https://fluca1978.github.io/2020/05/28/PostgreSQLWalNames.html>

and you can try pg_waldump
Who is spending wal crazily - Highgo Software Inc.
<https://www.highgo.ca/2020/08/28/who-is-spending-wal-crazily/>
to see what is in the WAL, and if you see any issues.

On Fri, 4 Jun 2021 at 18:45, Vijaykumar Jain <
vijaykumarjain(dot)github(at)gmail(dot)com> wrote:

> I have not seen this, so cannot comment, but when I am trying to simulate
> i do not see issues.
>
> One thing to note,
> It seems your wal is on nfs mount , can you rule out any nfs errors if it
> is nfs.
>
> On Fri, Jun 4, 2021, 6:24 PM Atul Kumar <akumar14871(at)gmail(dot)com> wrote:
>
>> Hi,
>>
>>
>> archive_command is 'cp %p /nfslogs/wal/%f'
>>
>> and no, we are not removing anything from pg_xlog directory.
>>
>> once old WAL files of pg_xlog directory are archived in
>> '/nfslogs/wal/' directory then these WAL files are getting generated
>> with the same name in pg_xlog directory.
>>
>> my query is Why is this happening ?
>>
>>
>>
>> please help me with your suggestions.
>>
>>
>> Regards.
>>
>>
>>
>>
>> On 6/4/21, Jehan-Guillaume de Rorthais <jgdr(at)dalibo(dot)com> wrote:
>> > On Fri, 4 Jun 2021 15:39:30 +0530
>> > Atul Kumar <akumar14871(at)gmail(dot)com> wrote:
>> >
>> >> HI,
>> >>
>> >> We have a centos 6 enviornment where postgres 9.6 is running on it.
>> >>
>> >> We have strange behavior of WAL files of pg_xlog directory
>> >>
>> >> As we have set archive_command to archive WAL files at different
>> >> location and the archive_command is working fine.
>> >>
>> >> So strange behavior is :
>> >>
>> >> We have a WAL file say for example "00000001000036CD000000E2" of
>> >> 01.06.2021 (1st June 2021) that is getting archive successfully at the
>> >> archive location and once it is archived, this file with same name
>> >> (00000001000036CD000000E2) is getting generated with the latest
>> >> timestamp (as today is 04.06.2021).and all old WAL files are behaving
>> >> in same manner.
>> >
>> > What is you archive_command?
>> >
>> > I'm not sure I understand correctly, but keep in mind your
>> > archive_command must be "read only". Do not remove the WAL file after
>> > archiving
>> > it.
>> >
>> > Regards,
>> >
>>
>>
>>

--
Thanks,
Vijay
Mumbai, India