Re: pg_xlog_replay_resume() considered armed and dangerous

On Thu, Mar 12, 2015 at 04:08:02PM +0100, Andres Freund wrote:
> Hi,
>
> I think it's quite confusing that a function named
> pg_xlog_replay_resume() can cause a node to be promoted.
>
> That this is happened is kind of documented in the recovery.conf section
> of the manual:
> "The intended use of the pause setting is to allow queries to be executed
> against the database to check if this recovery target is the most
> desirable point for recovery. The paused state can be resumed by using
> pg_xlog_replay_resume() (see Table 9-69), which then causes recovery to
> end. If this recovery target is not the desired stopping point, then
> shut down the server, change the recovery target settings to a later
> target and restart to continue recovery."
>
> But it's not mentioned at all in the section about the functions:
> http://www.postgresql.org/docs/devel/static/functions-admin.html#FUNCTIONS-RECOVERY-CONTROL-TABLE
>
> Promotion only happens when a node is paused due to a recovery target
> setting, and not when it's stopped due to pg_xlog_replay_pause().
>
> I think this, at the very least, needs a big caveat in the documentation
> of the resume function. But a different API would probably be
> better. I'd actually argue that for now pg_xlog_replay_resume() should
> refuse to work if paused due to a recovery target. Promotion should be
> done via the normal promotion methods.

Where are we on this?

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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