Re: User Interface for WAL usage data

On Fri, Apr 3, 2020 at 1:57 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Fri, Apr 3, 2020 at 11:29 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >
> > On Fri, Apr 3, 2020 at 11:14 AM Justin Pryzby <pryzby(at)telsasoft(dot)com> wrote:
> > >
> > > On Fri, Apr 03, 2020 at 10:52:02AM +0530, Amit Kapila wrote:
> > > > On Fri, Apr 3, 2020 at 10:41 AM Justin Pryzby <pryzby(at)telsasoft(dot)com> wrote:
> > > > >
> > > > > > > > > > > WAL: records=2359 full page records=42 bytes=447788
> > > > >
> > > > > 1) records; 2) pages ("full page images"); 3) bytes
> > > > >
> > > > > That is exactly like sort (method/type/size) and hash (buckets/batches/size),
> > > > > and *not* like buffers, which shows various values all in units of "pages".
> > > > >
> > > >
> > > > The way you have written (2) appears to bit awkward. I would prefer
> > > > "full page writes" or "full page images".
> > >
> > > I didn't mean it to be the description used in the patch or anywhere else, just
> > > the list of units.
> > >
> > > I wonder if it should use colons instead of equals ? As in:
> > > | WAL: Records: 2359 Full Page Images: 42 Size: 437kB
> > >
> > > Note, that has: 1) two spaces; 2) capitalized "fields"; 3) size rather than
> > > "bytes". That's similar to Buckets:
> > > | Buckets: 1024 Batches: 1 Memory Usage: 44kB
> > >
> > > I'm not sure if it should say "WAL: " or "WAL ", or perhaps "WAL: " If
> > > there's no colon, then it looks like the first field is "WAL Records", but then
> > > "size" isn't as tightly associated with WAL. It could say:
> > > | WAL Records: n Full Page Images: n WAL Size: nkB
> > >
> > > For comparison, buffers uses "equals" for the case showing multiple "fields",
> > > which are all in units of pages:
> > > | Buffers: shared hit=15 read=2006
> > >
> >
> > I think this is more close to the case of Buffers where all fields are
> > directly related to buffers/blocks. Here all the fields we want to
> > display are related to WAL, so we should try to make it display
> > similar to Buffers.
> >
>
> Dilip, Julien, others, do you have any suggestions here? I think we
> need to decide something now. We can change a few things like from
> 'two spaces' to 'one space' between fields later as well.

I also think it is more close to the BufferUsage so better to keep
similar to that. If we think the parsing is the problem we can keep
'_' in the multi-word name as shown below.
WAL: records=n full_page_writes=n bytes=n

And, all three fields are related to WAL so we can use WAL: followed
by other fields as we are doing now in the current patch.

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com