Re: Allow "snapshot too old" error, to prevent bloat

On Feb 17, 2015 12:26 AM, "Andres Freund" <andres(at)2ndquadrant(dot)com> wrote:
>
> On 2015-02-16 16:35:46 -0500, Bruce Momjian wrote:
> > It seems we already have a mechanism in place that allows tuning of
> > query cancel on standbys vs. preventing standby queries from seeing old
> > data, specifically
> > max_standby_streaming_delay/max_standby_archive_delay. We obsessed
> > about how users were going to react to these odd variables, but there
> > has been little negative feedback.
>
> FWIW, I think that's a somewhat skewed perception. I think it was right to
> introduce those, because we didn't really have any alternatives.
>
> But max_standby_streaming_delay, max_standby_archive_delay and
> hot_standby_feedback are among the most frequent triggers for questions
> and complaints that I/we see.
>

Agreed.

And a really bad one used to be vacuum_defer_cleanup_age, because of
confusing units amongst other things. Which in terms seems fairly close to
Kevins suggestions, unfortunately.

/Magnus