Re: a fast bloat measurement tool (was Re: Measuring relation free space)

Hi Andres.

I've attached an updated patch for pgstatbloat, as well as a patch to
replace two uses of BuildTupleFromCStrings() elsewhere in pgstattuple.

I've made the changes you mentioned in your earlier mail, except that I
have not changed the name pending further suggestions about what would
be the best name.

Also:

At 2015-05-09 15:36:49 +0530, ams(at)2ndQuadrant(dot)com wrote:
>
> At 2015-05-09 02:20:51 +0200, andres(at)anarazel(dot)de wrote:
> >
> > I haven't checked, but I'm not sure that it's safe/meaningful to
> > call PageGetHeapFreeSpace() on a new page.
>
> OK, I'll check and fix if necessary.

You're right, PageGetHeapFreeSpace() isn't safe on a new page. I've
added a guard to that call in the attached patch, but I'm not sure
that's the right thing to do.

Should I copy the orphaned new-page handling from lazy_scan_heap? What
about for empty pages? Neither feels like a very good thing to do, but
then neither does skipping the new page silently. Should I count the
space it would have free if it were initialised, but leave the page
alone for VACUUM to deal with? Or just leave it as it is?

-- Abhijit