Re: MultiXact member wraparound protections are now enabled

On 26 July 2015 at 20:15, Noah Misch <noah(at)leadboat(dot)com> wrote:

> On Fri, Jul 24, 2015 at 09:14:09PM -0400, Peter Eisentraut wrote:
> > On 7/22/15 4:45 PM, Robert Haas wrote:
> > > But it seemed to me that this could be rather confusing. I thought it
> > > would be better to be explicit about whether the protections are
> > > enabled in all cases. That way, (1) if you see the message saying
> > > they are enabled, they are enabled; (2) if you see the message saying
> > > they are disabled, they are disabled; and (3) if you see neither
> > > message, your version does not have those protections.
> >
> > But this is not documented, AFAICT, so I don't think anyone is going to
> > be able to follow that logic. I don't see anything in the release notes
> > saying, look for this message to see how this applies to you, or
> whatever.
>
> I supported inclusion of the message, because it has good potential to help
> experts studying historical logs to find the root cause of data corruption.
> The complex histories of clusters showing corruption from this series of
> bugs
> have brought great expense to the task of debugging new reports. Given a
> cluster having full mxact wraparound protections since last corruption-free
> backup (or since initdb), one can rule out some causes.

Would it be better to replace it with a less specific and more generally
useful message?

For example, Server started with release X.y.z
from which we could infer various useful things.

--
Simon Riggs http://www.2ndQuadrant.com/
<http://www.2ndquadrant.com/>
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services