Re: pageinspect: add tuple_data_record()

Hi,

On 2018-10-16 22:05:28 -0400, James Coleman wrote:
> > I don't think it's entirely safe to do so for invisible rows. The toast
> > references could be reused, constraints be violated, etc. So while I
> > could have used this several times before, it's also very likely a good
> > way to cause trouble. It'd probably be ok to just fetch the binary
> > value of the columns, but detoasting sure ain't ok.
> >
>
> Wouldn’t that be equally true for the already existing toast option to
> tuple_data_split()?

Yes. Whoever added that didn't think far enough. Teodor, Nikolay?

> Is “unsafe” here something that would lead to a crash? Or just returning
> invalid data? Given that pageinspect is already clearly an internal viewing
> of data, I think allowing invalid or limited data is a reasonable result.

Both.

> Alternatively, would returning only inline values be safe (and say,
> returning null for any toasted data)?

I think that'd be somewhat confusing.

I don't think it's necessarily just toast that's a problem here, that
was just an obvious point.

> Yes, though seems like maybe the style guide could be a bit more
> descriptive in some of these areas to be more friendly to newcomers. In
> contrast the wiki page for submitting a patch is extremely detailed.

I think there's a lot in that area we should improve.

Greetings,

Andres Freund