Re: could not link file in wal restore lines

My script does the following:

0. no processes running
1. rm -rf data_dir
2. mkdir -p data_dir
3. pgbackrest restore
4. start pg service

I don't know where could this come from or how should I start to debug it.
Also, if this is not critical then I can just stop worrying about it, but I
don't like having possible bugs in a DB restore process.

Zsolt

On 23. Jul 2022 at 05:36:47, Michael Paquier <michael(at)paquier(dot)xyz> wrote:

> On Fri, Jul 22, 2022 at 04:24:54AM -0500, Zsolt Ero wrote:
>
> I've opened an issue on pgbackrest, where the developer confirmed that
>
> those files are not touched by pgbackrest, they are basically copied back
>
> exactly as they were. The backup/restore is on the same partition as the
>
> data folder, so no chance of file system changes, etc. Single master, no
>
> replication.
>
>
> I'm always doing clean data dir + init_db so there is nothing there before
>
> the restore. I can replicate this behaviour 100%.
>
>
> PostgreSQL version: psql (PostgreSQL) 12.11 (Ubuntu 12.11-1.pgdg18.04+1)
>
>
> OS is Ubuntu 18.04
>
>
> pgbackrest issue: https://github.com/pgbackrest/pgbackrest/issues/1815
>
>
> log details:
>
>
> could not link file "pg_wal/000000010000015600000098" to
>
> "pg_wal/00000001000001570000006E": File exists
>
>
> FWIW, the backend code has protections to prevent *exactly* this kind
> of problems when recycling WAL segment files at checkpoints with a set
> of LWLocks taken on the control file, for one. Perhaps you have
> messed up things and you have finished in such a state that backrest
> writes to pg_wal/ concurrently with a cluster running and running a
> checkpoint, which would explain those link() calls to be failing?
> --
> Michael
>