Re: Race condition in recovery?

On Tue, May 25, 2021 at 9:16 PM Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> use FindBin;
>
> and then use $FindBin::RealBin to construct a path name to the executable, e.g.
>
> $node_primary->append_conf(
> 'postgresql.conf', qq(
> archive_command = '"$FindBin::RealBin/skip_cp" "%p" "$archivedir_primary/%f"'
> ));
>
> This avoids issues such as: leaving behind files if the script is
> terminated, needing the current working directory to be writable,
> possible permissions issues with the new file under Windows or
> SE-Linux.

Done

> The restore_command needs to be "cp" on Linux but "copy" on Windows.
> Maybe you can use PostgresNode.pm's enable_restoring? Or if that
> doesn't work, then you need to mimic the logic, as
> src/test/recovery/t/020_archive_status.pl does for archive_command.

Done

> Why do you set log_line_prefix? Is that needed?

No, it was not, removed

> Why are the nodes called standby_1 and cascade? Either use standby and
> cascade or standby_1 and standby_2.

Fixed

> There is a comment that says "Create some content on primary and check
> its presence in standby 1" but it only creates the content, and does
> not check anything. I think we don't really need to do any of this,
> but at least the code and the comment have to match.

I think we need to create some content on promoted standby and check
whether the cascade standby is able to get that or not, that will
guarantee that it is actually following the promoted standby, I have
added the test for that so that it matches the comments.

> Let's not call the command skip_cp. It's not very descriptive. If you
> don't like recalcitrant_cp, then maybe something like cp_history_files
> or so.

Done

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com