Re: shared-memory based stats collector - v70

On Wed, 10 Aug 2022 at 04:05, Drouvot, Bertrand <bdrouvot@amazon.com> wrote:
>
> Hi,
>
> On 8/9/22 6:00 PM, Greg Stark wrote:
> > On Tue, 9 Aug 2022 at 06:19, Drouvot, Bertrand <bdrouvot@amazon.com> wrote:
> >>
> >> What do you think about adding a function in core PG to provide such
> >> functionality? (means being able to retrieve all the stats (+ eventually
> >> add some filtering) without the need to connect to each database).
> > I'm working on it myself too. I'll post a patch for discussion in a bit.
>
> Great! Thank you!

So I was adding the code to pgstat.c because I had thought there were
some data types I needed and/or static functions I needed. However you
and Andres encouraged me to check again now. And indeed I was able,
after fixing a couple things, to make the code work entirely
externally.

This is definitely not polished and there's a couple obvious things
missing. But at the risk of embarrassment I've attached my WIP. Please
be gentle :) I'll post the github link in a bit when I've fixed up
some meta info.

I'm definitely not wedded to the idea of using callbacks, it was just
the most convenient way to get started, especially when I was putting
the main loop in pgstat.c.  Ideally I do want to keep open the
possibility of streaming the results out without buffering the whole
set in memory.

> Out of curiosity, would you be also interested by such a feature for
> previous versions (that will not get the patch in) ?

I always had trouble understanding the existing stats code so I was
hoping the new code would make it easier. It seems to have worked but
it's possible I'm wrong and it was always possible and the problem was
always just me :)


-- 
greg