Re: Reviewing freeze map code

On Mon, May 9, 2016 at 10:53 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Sun, May 8, 2016 at 10:42 PM, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>> Attached draft patch adds SCANALL option to VACUUM in order to scan
>> all pages forcibly while ignoring visibility map information.
>> The option name is SCANALL for now but we could change it after got consensus.
>
> If we're going to go that way, I'd say it should be scan_all rather
> than scanall. Makes it clearer, at least IMHO.

Just to add some diversity to opinions, maybe there should be a
separate command for performing integrity checks. Currently the best
ways to actually verify database correctness do so as a side effect.
The question that I get pretty much every time after I explain why we
have data checksums, is "how do I check that they are correct" and we
don't have a nice answer for that now. We could also use some ways to
sniff out corrupted rows that don't involve crashing the server in a
loop. Vacuuming pages that supposedly don't need vacuuming just to
verify integrity seems very much in the same vein.

I know right now isn't exactly the best time to hastily slap on such a
feature, but I just wanted the thought to be out there for
consideration.

Regards,
Ants Aasma