Re: what does this mean: "running xacts with xcnt == 0"

Andres Freund wrote:
> Hi,
>
> On 2014-11-12 09:03:40 -0500, Peter Eisentraut wrote:
> > Could someone translate this detail message to English:
> >
> > ereport(LOG,
> > (errmsg("logical decoding found consistent point at %X/%X",
> > (uint32) (lsn >> 32), (uint32) lsn),
> > errdetail("running xacts with xcnt == 0")));
>
> It means there a xl_running_xacts record was encountered that had xcnt =
> 0 - allowing logical decoding to find a consistent start point
>
> > (or downgrade to debug message, if appropriate)?
>
> The message generally is quite relevant, as the process of finding a
> consistent start point can take quite a while. we don't really have a
> nice way to make errdetail() only be logged on a certain severity level
> as far as I am aware off.

Can we do just the errmsg() and remove with the errdetail?

> So maybe 'Encountered xl_running_xacts record with xcnt = 0.'?

That's not very user-facing, is it -- I mean, why bother the user with
the names of structs and members thereof? It seems better to describe
what the condition is; something like "found point in time with no
running transaction". Maybe "point in time" should be "WAL record"
instead.

--
Álvaro Herrera http://www.2ndQuadrant.com/
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