Horton

Re: WAL usage calculation patch

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Dilip Kumar <dilipbalaut@gmail.com>
Cc: Julien Rouhaud <rjuju123@gmail.com>, Kuntal Ghosh <kuntalghosh.2007@gmail.com>, Fujii Masao <masao.fujii@oss.nttdata.com>, Kirill Bychik <kirill.bychik@gmail.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Thomas Munro <thomas.munro@gmail.com>
Date: 2020-04-03T02:43:47Z
Lists: pgsql-hackers

Commits

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  1. Change the display of WAL usage statistics in Explain.

  2. Cosmetic fixups for WAL usage work.

  3. Allow parallel create index to accumulate buffer usage stats.

  4. Allow autovacuum to log WAL usage statistics.

  5. Add the option to report WAL usage in EXPLAIN and auto_explain.

  6. Allow pg_stat_statements to track WAL usage statistics.

  7. Add infrastructure to track WAL usage.

  8. Include information on buffer usage during planning phase, in EXPLAIN output, take two.

  9. Include information on buffer usage during planning phase, in EXPLAIN output.

  10. Allow parallel vacuum to accumulate buffer usage.

  11. Allow pg_stat_statements to track planning statistics.

On Fri, Apr 3, 2020 at 6:37 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Thu, Apr 2, 2020 at 8:06 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> >
> > On Thu, Apr 2, 2020 at 6:41 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> > >
> > > 4.
> > > /* # of WAL full page image generated */
> > > Can we change it to "/* # of WAL full page image records generated */"?
> >
> > IMHO, "# of WAL full-page image records" seems like the number of wal
> > record which contains the full-page image.
> >
>
> I think this resembles what you have written here.
>
> >  But, actually, this is the
> > total number of the full-page images, not the number of records that
> > have a full-page image.
> >
>
> We count this when forming WAL records.  As per my understanding, all
> three counters are about WAL records.  This counter tells how many
> records have full page images and one of the purposes of having this
> counter is to check what percentage of records contain full page
> image.
>

How about if say "# of full-page writes generated" or "# of WAL
full-page writes generated"?  I think now I understand your concern
because we want to display it as full page writes and the comment
doesn't seem to indicate the same.

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com