Re: Reviewing freeze map code

Hi,

On 2016-06-06 17:22:38 -0400, Robert Haas wrote:
> > I'd also be ok with adding & documenting (beta release notes)
> > CREATE EXTENSION pg_visibility;
> > SELECT relname FROM pg_class WHERE relkind IN ('r', 'm') AND NOT pg_check_visibility(oid);
> > or something olong those lines.
> 
> That wouldn't be too useful as-written in my book, because it gives
> you no detail on what exactly the problem was.

True. I don't think that's a big issue though, because we'd likely want
a lot more detail after a report anyway; to analyze things properly.

> Maybe it could be
> "pg_check_visibility(regclass) RETURNS SETOF tid", where the returned
> TIDs are non-frozen TIDs on frozen pages.  Then I think something like
> this would work:
> 
> SELECT c.oid, pg_check_visibility(c.oid) FROM pg_class WHERE relkind
> IN ('r', 't', 'm');
> 
> If you get any rows back, you've got trouble.

That'd work too; with the slight danger of returning way too much data.

- Andres