Re: Add LSN along with offset to error messages reported for WAL file read/write/validate header failures

At Thu, 22 Dec 2022 10:09:23 +0530, Bharath Rupireddy <bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote in
> On Thu, Dec 22, 2022 at 7:57 AM Michael Paquier <michael(at)paquier(dot)xyz> wrote:
> >
> > On Wed, Dec 21, 2022 at 10:22:02PM +0100, Magnus Hagander wrote:
> > > Basically, we take one thing and turn it into 3. That very naturally rings
> > > with "split" to me.
> > >
> > > Parse might work as well, certainly better than dissect. I'd still prefer
> > > split though.
> >
> > Honestly, I don't have any counter-arguments, so I am fine to switch
> > the name as you are suggesting. And pg_split_walfile_name() it is?
>
> +1. FWIW, a simple patch is here
> https://www.postgresql.org/message-id/CALj2ACXdZ7WGRD-_jPPeZugvWLN%2Bgxo3QtV-eZPRicUwjesM%3Dg%40mail.gmail.com.

By the way the function is documented as the follows.

> Extracts the file sequence number and timeline ID from a WAL file name.

I didn't find the definition for the workd "file sequence number" in
the doc. Instead I find "segment number" (a bit doubtful, though..).

In the first place "file sequence number" and "segno" can hardly be
associated by appearance by readers, I think. (Yeah, we can identify
that since the another parameter is identifiable alone.) Why don't we
spell out the parameter simply as "segment number"?

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center