Re: User Interface for WAL usage data

At Thu, 2 Apr 2020 00:41:20 -0500, Justin Pryzby <pryzby(at)telsasoft(dot)com> wrote in
> On Thu, Apr 02, 2020 at 10:13:18AM +0530, Amit Kapila wrote:
> > In thread [1], we are discussing to expose WAL usage data for each
> > statement in a way quite similar to how we expose BufferUsage data.
> > The way it exposes seems reasonable to me and no one else raises any
> > objection. It could be that it appears fine to others who have
> > reviewed the patch but I thought it would be a good idea to write a
> > separate email just for its UI and see if anybody has objection.
>
> +1
>
> Regarding v10-0004-Add-option-to-report-WAL-usage-in-EXPLAIN-and-au.patch:
> I think there should be additional spaces before "full" and before "bytes":
>
> > WAL: records=2359 full page records=42 bytes=447788
>
> Compare with these:
>
> "Sort Method: %s %s: %ldkB\n",
> "Buckets: %d (originally %d) Batches: %d (originally %d) Memory Usage: %ldkB\n",
> "Buckets: %d Batches: %d Memory Usage: %ldkB\n",
>
> Otherwise "records=2359 full page records=42" is hard to parse.

I got the same feeling seeing the line.

"full page records" seems to be showing the number of full page
images, not the record having full page images.

> > Exposed via auto_explain
> > WAL: records=200 full page records=2 bytes=37387
>
> Same
>
> In v10-0002:
> + * BufferUsage and WalUsage during executing maintenance command can be
> should say "during execution of a maintenance command".
> I'm afraid that'll cause merge conflicts for you :(
>
> In 0003:
> + /* Provide WAL update data to the instrumentation */
> Remove "data" ??

--
Kyotaro Horiguchi
NTT Open Source Software Center