Re: WAL usage calculation patch

Amit Kapila <amit.kapila16@gmail.com>

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: 2020-04-03T03:32:41Z

Lists: pgsql-hackers

Commits

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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

On Fri, Apr 3, 2020 at 8:55 AM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>
> I think now I got the reason.  Basically, both of these records are
> storing the FPW, and FPW size can vary based on the hole size on the
> page.  If hold size is smaller the image length will be more, the
> image_len= BLCKSZ-hole_size.  So in subsequent records, the image size
> is bigger.
>

This means if we always re-create the database or may be keep
full_page_writes to off, then we should get consistent WAL usage data
for all tests.

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