Re: pgsql: Integrate recovery.conf into postgresql.conf

Hi

> The buildfarm is unhappy after this one:
> https://buildfarm.postgresql.org/cgi-bin/show_history.pl?nm=culicidae&br=HEAD
>
> If I use -DEXEC_BACKEND when compiling the tests complain about a
> timeout in 003_recovery_targets. Here is what the buildfarm reports, I
> can see the failure by myself as well:
> # Postmaster PID for node "standby_6" is 26668
> # poll_query_until timed out executing this query:
> # SELECT '0/3022690'::pg_lsn <= pg_last_wal_replay_lsn()
> # expecting this output:
> # t
> # last actual query output:
> # f
> # with stderr:
> Timed out while waiting for standby to catch up at
> t/003_recovery_targets.pl line 34.

I can reproduce this and notice wrong assign settings order. For example standby_6 has
> recovery_target_name = '$recovery_name'
> recovery_target_xid = '$recovery_txid'
> recovery_target_time = '$recovery_time'
But recoveryTarget was set to RECOVERY_TARGET_XID
Without -DEXEC_BACKEND all fine.

As far as I understand the guc.c code with EXEC_BACKEND all processes uses different config processing logic. We serialize all GUC and restore at process start. And we sort GUC by name in build_guc_variables - so we restore settings in wrong order. I was afraid that the GUC system does not guarantee the order of settings...

What is preferable solution? Seems we can not simple change this logic.
I think i can reorganize all new recovery_target_* GUC into single one with format, for example, recovery_target = "xid:607" (was mentioned in patch discussion).

regards, Sergei