Re: WAL usage calculation patch

Julien Rouhaud <rjuju123@gmail.com>

From: Julien Rouhaud <rjuju123@gmail.com>

To: Justin Pryzby <pryzby@telsasoft.com>

Cc: Amit Kapila <amit.kapila16@gmail.com>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, Dilip Kumar <dilipbalaut@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: 2020-04-19T14:22:26Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Change the display of WAL usage statistics in Explain.
- 69bfaf2e1de4 13.0 landed
Cosmetic fixups for WAL usage work.
- ef08ca113fe3 13.0 landed
Allow parallel create index to accumulate buffer usage stats.
- 5c71362174eb 13.0 landed
- f179e9f01b65 11.8 landed
- 13823ad3b012 12.3 landed
Allow autovacuum to log WAL usage statistics.
- b7ce6de93b59 13.0 landed
Add the option to report WAL usage in EXPLAIN and auto_explain.
- 33e05f89c53e 13.0 landed
Allow pg_stat_statements to track WAL usage statistics.
- 6b466bf5f2be 13.0 landed
Add infrastructure to track WAL usage.
- df3b181499b4 13.0 landed
Include information on buffer usage during planning phase, in EXPLAIN output, take two.
- ce77abe63cfc 13.0 cited
Include information on buffer usage during planning phase, in EXPLAIN output.
- ed7a5095716e 13.0 cited
Allow parallel vacuum to accumulate buffer usage.
- 3a5e22138a8d 13.0 landed
Allow pg_stat_statements to track planning statistics.
- 17e03282241c 13.0 cited

Attachments

v2-fix_explain_wal_output.diff (text/x-patch) patch v2

Hi Justin,

Thanks for the review!

On Sat, Apr 18, 2020 at 10:41 PM Justin Pryzby <pryzby@telsasoft.com> wrote:
>
> Should capitalize at least the non-text one ?  And maybe the text one for
> consistency ?
>
> +               ExplainPropertyInteger("WAL fpw", NULL,

I think we should keep both version consistent, whether lower or upper
case.  The uppercase version is probably more correct, but it's a
little bit weird to have it being the only upper case label in all
output, so I kept it lower case.

> And add the acronym to the docs:
>
> $ git grep 'full page' '*/explain.sgml'
> doc/src/sgml/ref/explain.sgml:      number of records, number of full page writes and amount of WAL bytes
>
> "..full page writes (FPW).."

Indeed!  Fixed (using lowercase to match current output).

> Should we also change vacuumlazy.c for consistency ?
>
> +                                                        _("WAL usage: %ld records, %ld full page writes, "
> +                                                          UINT64_FORMAT " bytes"),

I don't think this one should be changed, vacuumlazy output is already
entirely different, and is way more verbose so keeping it as is makes
sense to me.