Horton

Re: WAL usage calculation patch

Peter Eisentraut <peter.eisentraut@2ndquadrant.com>

View thread
From: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
To: Amit Kapila <amit.kapila16@gmail.com>, Justin Pryzby <pryzby@telsasoft.com>
Cc: Dilip Kumar <dilipbalaut@gmail.com>, 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: 2020-04-07T10:00:29Z
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 2020-04-07 04:12, Amit Kapila wrote:
> On Mon, Apr 6, 2020 at 10:01 PM Justin Pryzby <pryzby@telsasoft.com> wrote:
>>
>> On Mon, Apr 06, 2020 at 05:01:30PM +0200, Peter Eisentraut wrote:
>>> I noticed in some of the screenshots that were tweeted that for example in
>>>
>>>      WAL:  records=1  bytes=56
>>>
>>> there are two spaces between pieces of data.  This doesn't match the rest of
>>> the EXPLAIN output.  Can that be adjusted?
>>
>> We talked about that here:
>> https://www.postgresql.org/message-id/20200402054120.GC14618%40telsasoft.com
>>
> 
> Yeah.  Just to brief here, the main reason was that one of the fields
> (full page writes) already had a single space and then we had prior
> cases as mentioned in Justin's email [1] where we use two spaces which
> lead us to decide using two spaces in this case.

We also have existing cases for the other way:

     actual time=0.050..0.052
     Buffers: shared hit=3 dirtied=1

The cases mentioned by Justin are not formatted in a key=value format, 
so it's not quite the same, but it also raises the question why they are 
not.

Let's figure out a way to consolidate this without making up a third format.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services