Horton

Re: WAL usage calculation patch

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Julien Rouhaud <rjuju123@gmail.com>
Cc: Kirill Bychik <kirill.bychik@gmail.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Craig Ringer <craig@2ndquadrant.com>, Thomas Munro <thomas.munro@gmail.com>
Date: 2020-03-05T06:35:48Z
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 →

  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 Wed, Mar 04, 2020 at 05:02:25PM +0100, Julien Rouhaud wrote:
> I'm quite worried about the stability of those counters for regression tests.
> Wouldn't a checkpoint happening during the test change them?

Yep.  One way to go through that would be to test if this output is
non-zero still I suspect at quick glance that this won't be entirely
reliable either.

> While at it, did you consider adding a full-page image counter in the WalUsage?
> That's something I'd really like to have and it doesn't seem hard to integrate.

FWIW, one reason here is that we had recently some benchmark work done
internally where this would have been helpful in studying some spiky
WAL load patterns.
--
Michael