Horton

Re: pg_stat_get_backend_subxact() and backend IDs?

Nathan Bossart <nathandbossart@gmail.com>

View thread View on postgr.es
From: Nathan Bossart <nathandbossart@gmail.com>
To: Ian Lawrence Barwick <barwick@gmail.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>, robertmhaas@gmail.com
Date: 2023-08-24T02:51:40Z
Lists: pgsql-hackers 
On Wed, Aug 23, 2023 at 07:32:06PM -0700, Nathan Bossart wrote:
> On Thu, Aug 24, 2023 at 10:22:49AM +0900, Ian Lawrence Barwick wrote:
>> Looking at the code, this is happening because
>> "pgstat_fetch_stat_local_beentry()"
>> expects to be passed the backend ID as an integer representing a 1-based index
>> referring to "localBackendStatusTable", but "pg_stat_get_backend_subxact()"
>> is presumably intended to take the actual BackendId , as per other
>> "pg_stat_get_XXX()"
>> functions.
> 
> Yes, this was changed in d7e39d7, but 10ea0f9 seems to have missed the
> memo.

BTW I'd argue that this is a bug in v16 that we should try to fix before
GA, so I've added an open item [0].  I assigned it to Robert (CC'd) since
he was the committer, but I'm happy to pick it up.

[0] https://wiki.postgresql.org/wiki/PostgreSQL_16_Open_Items#Open_Issues

-- 
Nathan Bossart
Amazon Web Services: https://aws.amazon.com

Commits

  1. Use actual backend IDs in pg_stat_get_backend_subxact().

  2. Rename some support functions for pgstat* views.

  3. Expose some information about backend subxact status.