pg_ctl wait exit code (was Re: [COMMITTERS] pgsql: Additional tests for subtransactions in recovery)

On 4/27/17 08:41, Michael Paquier wrote:
> +$node_slave->promote;
> +$node_slave->poll_query_until('postgres',
> + "SELECT NOT pg_is_in_recovery()")
> + or die "Timed out while waiting for promotion of standby";
>
> This reminds me that we should really switch PostgresNode::promote to
> use the wait mode of pg_ctl promote, and remove all those polling
> queries...

I was going to say: This should all be obsolete already, because pg_ctl
promote waits by default.

However: Failure to complete promotion within the waiting time does not
lead to an error exit, so you will not get a failure if the promotion
does not finish. This is probably a mistake. Looking around pg_ctl, I
found that this was handled seemingly inconsistently in do_start(), but
do_stop() errors when it does not complete.

Possible patches for this attached.

Perhaps we need a separate exit code in pg_ctl to distinguish general
errors from did not finish within timeout?

--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services