Re: pg_walinspect - a new extension to get raw WAL data and WAL stats

Thanks Bharath for working on all my review comments. I took a quick
look at the new version of the patch (v7-pg_walinspect.patch) and this
version looks a lot better. I'll do some detailed review later (maybe
next week or so) and let you know my further comments, if any.

--
With Regards,
Ashutosh Sharma.

On Fri, Mar 4, 2022 at 3:54 PM Bharath Rupireddy
<bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:
>
> On Thu, Mar 3, 2022 at 10:05 PM Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> >
> > On Fri, Feb 25, 2022 at 6:03 AM Bharath Rupireddy
> > <bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:
> > > Added a new function that returns the first and last valid WAL record
> > > LSN of a given WAL file.
> >
> > Sounds like fuzzy thinking to me. WAL records can cross file
> > boundaries, and forgetting about that leads to all sorts of problems.
> > Just give people one function that decodes a range of LSNs and call it
> > good. Why do you need anything else? If people want to get the first
> > record that begins in a segment or the first record any portion of
> > which is in a particular segment or the last record that begins in a
> > segment or the last record that ends in a segment or any other such
> > thing, they can use a WHERE clause for that... and if you think they
> > can't, then that should be good cause to rethink the return value of
> > the one-and-only SRF that I think you need here.
>
> Thanks Robert.
>
> Thanks to others for your review comments.
>
> Here's the v7 patch set. These patches are based on the motive that
> "keep it simple and short yet effective and useful". With that in
> mind, I have not implemented the wait mode for any of the functions
> (as it doesn't look an effective use-case and requires adding a new
> page_read callback, instead throw error if future LSN is specified),
> also these functions will give WAL information on the current server's
> timeline. Having said that, I'm open to adding new functions in future
> once this initial version gets in, if there's a requirement and users
> ask for the new functions.
>
> Please review the v7 patch set and provide your thoughts.
>
> Regards,
> Bharath Rupireddy.