Horton

Re: Move wal_buffers_full to WalUsage (and report it in pgss/explain)

Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

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From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Ilia Evdokimov <ilya.evdokimov@tantorlabs.com>
Cc: pgsql-hackers@lists.postgresql.org
Date: 2025-02-11T14:05:18Z
Lists: pgsql-hackers 
Hi,

On Tue, Feb 11, 2025 at 03:30:09PM +0300, Ilia Evdokimov wrote:
> Hi,
> 
> Thank you for your work!

Thanks for the review!

> 1. Perhaps In EXPLAIN you forget to check that usage->wal_buffers_full > 0:
> 
> if ((usage->wal_records > 0) || (usage->wal_fpi > 0) || (usage->wal_bytes >
> 0))

I don't think that's possible to have wal_buffers_full > 0 if the above returns
false. A check is done at appendStringInfo() time so I think that's ok as it is.

> 2. I have a small suggestion for pg_stat_statements: would it make sense to
> move wal_buffers_full next to wal_records, wal_fpi and wal_bytes? This way,
> all WAL-related information would be grouped together.

I think I prefer to add it in "append" order. That way, that does not break
queries that rely on ordinal numbers.

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com

Commits

  1. Add information about WAL buffers full to VACUUM/ANALYZE (VERBOSE)

  2. Add information about WAL buffers being full to EXPLAIN (WAL)

  3. pg_stat_statements: Add wal_buffers_full

  4. Move wal_buffers_full from PgStat_PendingWalStats to WalUsage

  5. pg_stat_statements: Add columns to track parallel worker activity