Re: BUG #17928: Standby fails to decode WAL on termination of primary

On Sat, Sep 16, 2023 at 6:00 PM Alexander Lakhin <exclusion@gmail.com> wrote:
> It looks like the construction "@{^CAPTURE}" used in scan_server_header()
> is not supported by Perl 5.24, which is included in Debian stretch:
> https://perldoc.perl.org/variables/@%7B%5ECAPTURE%7D
> I replaced it with
> @match = ($1);
> and that worked for me.

Thanks for catching that!  I see that %{^CAPTURE} was added to Perl
5.25.7, but we document Perl 5.14 or later as the requirement
currently, and for REL_12_STABLE it's Perl 5.8.3.  That would
certainly have turned a few build farm fossils red.

Your replacement only returns the first captured group.  I don't know
Perl, but I think we can just assign the whole array to @match
directly, to maintain the semantics that Michael wanted, like so:

-               if ($line =~ /^$regexp/)
+               if (@match = $line =~ /^$regexp/)
                {
-                       # Found match, so store all the results.
-                       @match = @{^CAPTURE};
                        last;
                }

Better Perl welcome.

Looking into your observation about wal_log_hints...